DAIRY   TECHNOLOGY 

A   TREATISE   ON   THE    CITY   MILK   SUPPLY,    MILK   AS 

A   FOOD,   ICE   CREAM   MAKING,    BY-PRODUCTS   OF 

THE  CREAMERY  AND  CHEESERY,  FERMENTED 

MILKS,   CONDENSED   AND   EVAPORATED 

MILKS,  MILK  POWDER,  RENOVATED 

BUTTER,  AND  OLEOMARGARINE 


BY 

C.    LARSEN,   M.  S.  A. 

Professor  of  Dairy  Husbandry,  South  Dakota  State  College,  Brook  ings, 
,  South  Dakota 

AND 

WM.  WHITE,   B.  S. 


FIRST  EDITION 
FIRST    THOUSAND 


NEW    YORK 

JOHN    WILEY   &   SONS 
LONDON:    CHAPMAN    &    HALL,    LIMITED 


L3 


Main  Lib. 


COPYRIGHT,  1913, 

BY 
C.  LARSEN  AND  WM.   WHITE 


Stanhope  ipress 

F.    H.  GILSON   COMPANT 
BOSTON,  U.S.A. 


PREFACE. 


THE  manufacture  of  butter  and  cheese  has  been  carried 
on  by  man  from  time  immemorial.  But  there  are  uses 
of  milk  and  its  products  that  are  comparatively  new. 
Modern  man  has  invented  and  discovered  many  ways  of 
increasing  the  commercial  value  of  milk  and  its  products 
by  using  them  for  a  great  variety  of  purposes. 

These  uses  for  milk  are  here  grouped  together  and  treated 
under  the  one  head  —  "  Dairy  Technology."  This  sub- 
ject treats  of  the  production  and  preparation  of  sanitary, 
certified,  modified,  fermented,  dried  and  condensed  milks, 
the  manufacture  of  ice  cream,  renovated  butter,  oleo- 
margarine, milk  sugar,  casein,  etc. 

At  the  present  time  information  on  these  subjects  is 
widely  scattered  and  somewhat  indefinite.  It  is  the  pur- 
pose of  this  work  to  give  experiences  and  results  of  work 
carried  on  by  the  authors;  to  secure  from  bulletins,  papers, 
addresses,  and  other  sources,  reliable  data  dealing  with 
these  subjects;  and  to  compile  and  arrange  this  material 
in  such  manner  as  to  be  a  ready  reference  for  the  student 
of  this  phase  of  dairying. 

The  authors  realize  that  many  of  the  subjects  treated 
are  in  the  midst  of  a  transitional  period.  Future  experi- 
ments are  likely  to  add  valuable  information.  The  writers 
have  endeavored  to  obtain  the  best  possible  present  in- 
formation along  the  various  lines  discussed,  and  they  hope 
to  make  changes  and  additions  as  rapidly  as  the  authentic 
information  can  be  secured. 

iii 

267877 


CONTENTS. 


PART  I. 

MILK  AS  A  FOOD. 
CHAPTER  I. 

PAGE 

MILK  —  ITS  PROPERTIES  AND  COMPOSITION i 

What  is  Milk  ? i 

Properties  of  Milk i 

Composition  of  Milk 3 

CHAPTER  II. 

NORMAL  MILK  AND  ITS  PRODUCTS  AS  FOOD 5 

Palatability  of  Cows'  Milk 7 

Digestibility  of  Milk 8 

Raw  vs.  Heated  Milk 9 

Use  of  Milk  with  Other  Foods 9 

Relative  Cost  of  Milk 10 

Skim  Milk 14 

Buttermilk 17 

Cream 18 

Butter 19 

Cheddar  Cheese 20 

Cottage  Cheese 21 

CHAPTER  III. 

ABNORMAL  MILK 23 

Poisonous  Milk 23 

Colored  Milk 24 

Bitter  Milk 24 

Stringy  or  Ropy  Milk 24 

Colostrum 24 

General , 25 

v 


VI  CONTENTS 

PART   II. 

CITY  MILK  SUPPLY. 

CHAPTER  IV. 

PAGE 

EXTENT  AND  IMPORTANCE  OF  THIS  INDUSTRY 27 

Condition  of  City  Milk  Supply  in  Past  Years 29 

Investigations  in  Illinois  Cities 29 

Milk  and  Infant  Mortality 30 

Epidemics  Spread  by  Milk 32 

Sources  of  Milk  Contamination 32 

Bovine  Tuberculosis 33 

CHAPTER  V. 

IMPROVEMENT  -OF  THE  MILK  SUPPLY 35 

Inspection  of  Dairy  Farms  and  of  Milk 35 

Cost  of  Inspection 36 

The  Score  Card 37 

Advantages  of  Score  Card  Inspection 41 

Results  of  Score  Card  Inspection 42 

Inspection  of  City  Milk  Plants 43 

Milk  and  Cream  Contests 45 

Number  of  Inspections  made  in  New  York  City 47 

Limitations  of  General  Inspection 47 

Classes  of  Milk 48 

1.  Certified 49 

2.  Inspected 49 

3.  Pasteurized 50 

4.  Modified 51 

Results  of  the  Improvement  of  Milk  Supply 51 

Infants'  Milk  Depots  in  New  York 52 

Milk  Depots  in  Other  Cities 53 

CHAPTER  VI. 

CERTIFIED  MILK 55 

Origin  of  the  Term  "  Certified  Milk  " 55 

The  First  Medical  Milk  Commission 57 

Milk  Commissions 57 

Requirements  of  the  Milk  Commission  of  New  York  City 57 

Details  of  the  Workings  of  Various  Commissions 64 


CONTENTS  Vii 

PAGE 

Use  of  Certified  Milk 64 

Production  of  Certified  Milk 65 

INSPECTED  MILK 66 


CHAPTER  VII. 

PASTEURIZED  MILK 67 

Alleged  Disadvantages  of  Pasteurization 68 

1.  Promotes  Carelessness 68 

2.  Produces  Chemical  Changes : 69 

3.  Does  not  Kill  all  Undesirable  Germs 69 

4.  Toxic  By-products  Remain  in  Milk 72 

5.  Covers  Some  Defects  of  Milk 72 

6.  Affects  Flavor  and  Creaming  Property 72 

7.  Cost  of  Pasteurization 73 

Advantages  of  Pasteurization 75 

1.  Protection  against  Abnormal  and  Pathogenic  Bacteria. . .  75 

2.  Decreases  the  Total  Number  of  Bacteria 75 

3.  Pasteurized  Milk  Keeps  Longer 77 

Pasteurization  of  Milk  Increasing 77 

Official  Supervision  of  Pasteurization 77 

Laws  and  Ordinances  Pertaining  to  Pasteurization 78 

Home  Pasteurization 79 

CHAPTER  VIII. 

MODIFIED  MILK 80 

Use  of  Modified  Milk 80 

Digestibility  of  Modified  Milk 80 

1.  Composition  of  Human  Milk  (Colostrum  and  Normal) ....  81 

2.  Normal  Human  Milk  Compared  with  Cows'  Milk 81 

Food  Requirements  of  Infants 82 

Methods  for  Modifying  Milk 83 

Homogenized  Milk 84 


CHAPTER  IX. 

THE  VILLAGE  MILK  PLANT 87 

Objectionable  Practices 87 

Equipment  of  the  Plant 89 

1.  Cooling  the  Milk 89 

2.  Bottling  the  Milk 89 

3.  Bottle  Washing 92 


viii  CONTENTS 

CHAPTER  X.  PAGE 

THE  CITY  MILK  PLANT 94 

Transportation 94 

The  Intake 96 

Sanitary  Piping 97 

Clarifying 97 

Pasteurization  and  Cooling .  .  .  . 98 

Pasteurizers 100 

Pasteurization  in  the  Bottle. 101 

Bottling 104 

Delivering 105 

Bottle  Washing 105 

The  Milk  Bottle 109 

The  Bottle  Cap no 

Business  Principles in 

CHAPTER  XI. 

STANDARDIZATION  or  MILK  AND  CREAM 114 

Standardization  of  Milk 115 

Standardization  of  Cream 119 

CHAPTER  XII. 

SANITARY  EXAMINATION  OF  MILK  ; 1 23 

Acidity  Test 123 

Sediment  Test 1 24 

Leucocytes  in  Milk 125 

Reduction-Fermentation  Test 126 

CHAPTER  XIII. 

WHIPPING  OF  CREAM 127 

Conditions  Affecting  Viscosity  of  Cream 127 

Preparing  Viscogen 127 

Use  of  Viscogen  in  Cream , 128 

PART   III. 

ICE   CREAM   MAKING. 

CHAPTER  XIV. 

ICE  CREAM  MAKING 132 

History  and  Extent  of  Ice  Cream  Making 132 

Classification  of  Ice  Cream  and  Ices 135 


CONTENTS  ix 
CHAPTER  XV. 

PAGE 

CREAM  FOR  ICE  CREAM  MAKING 139 

Acidity 139 

Homogenized  Cream 140 

Pasteurization 141 

Aging  and  Cooling 142 

Fat  Content 142 

CHAPTER  XVI. 

PREPARING  THE  Mix.     FILLERS  AND  BINDERS 143 

Flavor 143 

1.  Crushed  Fruits 144 

2.  Extracts 144 

3.  Sweetening 144 

Fillers  and  Binders 146 

CHAPTER  XVII. 

FREEZING  THE  Mix 150 

Ice  and  Salt 150 

Speed  of  Dasher 153 

Freezing  Period 153 

Freezing  Point 154 

Effect  of  the  Sugar  Content  on  the  Freezing  Point 155 

Swell 155 

Stopping  Point 157 

Hardening 157 

Returned  Goods 157 

Fancy  Ice  Cream 158 

Fat  Content  of  Different  Portions 159 

CHAPTER  XVIII. 

FORMULAS 160 

Vanilla  Ice  Cream 160 

Fruit  Ice  Cream 161 

Parfait 161 

Mousse '. 161 

Lacto 162 

Sherbet  . '. ' 162 

CHAPTER  XIX. 

ICE  CREAM  MACHINERY 163 

Freezers 165 

Ice  Crusher 169 


X  CONTENTS 

PAGE 

Homogenizer 169 

Sanitary  Pipes  and  Fittings 171 

Ice  Cream  Can-Washer 171 

Packing  Cans 171 

Sterilizer 172 

CHAPTER  XX. 

ICE  CREAM  FACTORIES 173 

Local  Creameries 1 73 

Advantages 174 

Cost  of  Equipment 175 

Profits  from  this  Product 175 

The  Large  City  Factory 1 76 

Homogenized  Cream 176 

Making  the  Mix 178 

Freezing  and  Hardening 178 

Standardization  of  Cream 180 

CHAPTER  XXL 

SCORING  ICE  CREAM 182 

Proposed  Score  Cards 182 

CHAPTER  XXII. 

ICE  CREAM  STANDARDS 186 

Binders  and  Fillers 186 

Fat  Standard 186 

Testing  Ice  Cream 188 

1.  Hydrochloric  and  Acetic  Acid  Method 188 

2.  Modified  Babcock  Method 189 

Bacteria  in  Ice  Cream 189 

CHAPTER  XXIII. 

MECHANICAL  REFRIGERATION 193 

Chemicals  Used 193 

Principles  of  Producing  Cold  Artificially 194 

Transferring  the  Cold 196 

Use  of  Brine 197 

Strength  of  Brine 198 

Size  of  Compressor 198 

Operation  of  an  Ammonia  Plant 198 

Insulation. .  201 


CONTENTS  Xl 
PART   IV. 

BY-PRODUCTS  OF  THE  CREAMERY  AND  CHEESE  FACTORY. 

CHAPTER  XXIV.  PAGE 

COTTAGE  CHEESE 203 

Milk  to  Use 203 

Use  of  Starters 204 

Souring  the  Milk 204 

Heating  the  Curd 205 

Draining  the  Curd 205 

Seasoning  the  Curd 205 

Yield  of  Cheese 205 

Use  of  Rennet  in  Cottage  Cheese  Making 206 

Use  of  Hydrochloric  Acid 206 

BUTTERMILK  CHEESE 207 

Heating  the  Buttermilk 207 

Draining  the  Curd 208 

Seasoning  the  Curd 208 

Kind  of  Buttermilk 209 

Buttermilk  Cream 210 

CHAPTER  XXV. 

WHEY  BUTTER 211 

Original  Methods  of  Making  Whey  Butter 212 

Poor  Methods  Employed 213 

Modern  Whey  Butter  Making 213 

Disposal  of  Whey  Butter 214 

Profits  from  Whey  Butter  Making 215 

CHAPTER  XXVI. 

MILK  SUGAR 216 

History  and  Development  of  Milk  Sugar  Manufacturing 216 

Milk  Sugar  Making  in  the  United  States 217 

The  Process  of  Manufacture 218 

By-products  of  Milk  Sugar  Making 219 

Mysost 219 

CHAPTER  XXVII. 

CASEIN 221 

Preparation  of  Casein 221 

Casein  from  Buttermilk 224 


xii  CONTENTS 

PAGE 

Casein  Glue 225 

Casein  Paints 226 

Milk-Cement  Paint 226 

Plastic  Masses  from  Casein 227 

Manufacture  of  Galalith 228 

Casein  in  the  Textile  Industry 229 

Casein  Foodstuffs , 230 

Casein  in  the  Paper  Industry 230 

Other  Uses  for  Casein 231 

Buttermilk  Poultry  Food 231 

CHAPTER  XXVIII. 

FERMENTED  MILKS 232 

Food  Value 232 

Principles  Involved -.  . .  232 

Tablet  and  Capsule  Cultures : 233 

Buttermilk 234 

Composition 234 

Artificial  Buttermilk 235 

Bacillus  Bulgaricus  for  Buttermilk 236 

Buttermilk  Tablets • 237 

Kefir 238 

Kumiss 241 

American  Kefir  or  Kumiss 242 

Yoghurt,  etc 244 

Ropy  Milk 245 

Moscow  Sour  Cream 245 

Clotted  or  Devonshire  Cream 246 

Carbonated  Milk 247 

CHAPTER  XXIX. 

CONDENSED  AND  EVAPORATED  MILK 249 

Extent  of  the  Industry 249 

U.  S.  Standards 250 

Quality  of  Raw  Product 251 

The  Condensing  Process 253 

Degree  of  Concentration 255 

Sterilization 259 

Shaking  the  Canned  Milk 260 

Composition  of  Evaporated  Milk 261 

Composition  of  Sweetened  Condensed  Milk 261 

Relatively  Large  Investment  Needed 262 


CONTENTS  xiii 

CHAPTER  XXX.  PAGE 

MILK  POWDER 264 

Advantages  of  Milk  Powder 264 

History  and  Development  of  Milk  Desiccation 265 

The  Modern  Method 267 

Use  of  Milk  Powder '. . .  268 

Composition 269 

Whey  Powder  or  Dried  Whey 269 

CHAPTER  XXXI. 

RENOVATED  BUTTER 270 

Ladles 270 

Origin  of  Renovated  Butter 271 

Extent  of  the  Industry 271 

The  Processes  of  Manufacture 272 

Melting 272 

Refining  the  Oil 273 

Making  the  Emulsion 273 

Crystallizing  the  Fat 273 

Working  and  Salting 274 

Extracts  from  U.  S.  Laws  Relating  to  Renovated  Butter 274 

Test  for  Renovated  Butter 276 

CHAPTER  XXXII. 

OLEOMARGARINE 277 

Origin  of  Oleomargarine 277 

The  Original  Process 278 

Developments  in  the  Industry 278 

Manufacture  of  Oleomargarine 279 

Formulas  Used ; 281 

Quantity  Produced 284 

Food  Value ._ 284 

Oleomargarine  Law 286 

Detection  of  Oleomargarine 287 


DAIRY  TECHNOLOGY 

PART    I. 
MILK   AS   A    FOOD. 

CHAPTER    I. 

MILK  — ITS  PROPERTIES  AND   COMPOSITION. 

What  is  Milk?  —  According  to  the  government  stand- 
ard, "  Milk  is  the  lacteal  secretion  obtained  by  the  com- 
plete milking  of  one  or  more  healthy  cows,  properly  fed 
and  kept,  excluding  that  obtained  within  fifteen  days 
before  and  five  days  after  calving." 

Milk  is  a  fluid  secreted  by  females  of  the  mammalian 
group  for  the  special  purpose  of  providing  their  young  with 
a  proper  food.  It  is  a  watery  solution  of  milk  sugar,  albu- 
men and  mineral  salts,  containing  casein  and  fat  in  sus- 
pension. 

The  only  milk  of  great  commercial  importance  to  man 
is  that  of  the  cow.  Unless  otherwise  specified,  therefore, 
the  word  "  milk  "  always  refers  to  the  product  of  the  cow. 

Properties  of  Milk.  —  Milk  ranges  in  color  from  a  bluish 
white  to  a  golden  yellow,  depending  upon  the  breed  of  the 
animal,  the  food  consumed,  and  the  season  of  the  year. 
It  appears  completely  opaque  when  in  large  quantities, 
but  in  thin  layers  is  slightly  transparent.  When  freshly 
drawn  it  possesses  a  characteristic  odor.  This  animal 
odor  is  very  volatile  and  soon  escapes  from  the  milk,  if 

i 


2  DAIRY  TECHNOLOGY 

left  exposed  to  the  air.  The  flavor  of  milk  is  slightly  sweet- 
ish. Fresh  milk  has  an  amphoteric  reaction,  turns  red 
litmus  paper  blue  and  blue  litmus  paper  red.  This  re- 
action, so  far  as  known,  is  due  to  the  presence  of  phosphates 
in  the  milk.  Fresh  milk,  however,  appears  acid  to  phenol- 
phthalein,  and  when  titrated  with  tenth-normal  alkali 
shows  an  apparent  acidity  of  from  o.io  to  0.14  per  cent. 
This  acidity  is  undoubtedly  due  to  the  presence  in  the 
milk  of  phosphates,  citrates,  casein  and  carbon  dioxide. 

The  viscosity  of  milk  is  greater  than  that  of  water.  It 
is  increased  by  age,  low  temperature,  products  of  fermen- 
tation and  a  high  solid  and  fat  content.  The  viscosity 
of  milk  is  decreased  by  high  temperature,  a  low  solid  and 
fat  content  and  certain  fermentations. 

Milk  possesses  a  certain  adhesive  property.  It  sticks 
to  wood,  glass  and  metals  to  a  greater  degree  than  does 
water.  A  paper  moistened  with  milk  or  cream  makes  a 
label  that  will  stick  to  any  dry  object.  A  similar  paper 
moistened  with  skimmed  milk  has  less  adhesive  power. 
The  adhesive  property  of  milk  is  in  part  dependent  upon 
the  nitrogenous  matter.  This  fact  is  made  use  of  in  paint- 
ing and  whitewashing.  The  addition  of  milk  causes  the 
paint  to  adhere  better.  When  milk  is  allowed  to  stand  at 
room  temperature,  it  undergoes  fermentation;  lactic  acid 
is  formed  and  the  milk  becomes  thick  and  curdled.  The 
curdling  of  milk  may  be  produced  by  the  addition  of  any 
dilute  acid.  If  the  milk  thus  curdled  is  neutralized  with  an 
alkali,  such  as  lime  water,  ammonia  or  potash,  the  curd  is 
redissolved.  Milk  may  also  be  curdled  by  rennet  or  pepsin, 
and  the  curd  thus  produced  cannot  so  easily  be  redissolved 
by  weak  alkali  solutions. 

Milk  is  slightly  heavier  than  water;  its  specific  gravity 
varies  from  1.029  to  1.034  at  60°  F. 


MILK  — ITS  PROPERTIES  AND   COMPOSITION  3 

The  specific  heat  of  milk  is  less  than  that  of  water; 
that  is,  it  requires  less  heat  to  warm  a  definite  amount  of 
milk  one  degree.  It  also  takes  less  ice  to  cool  a  certain 
volume  of  milk  one  degree  than  it  does  to  cool  the  same 
quantity  of  water  one  degree.  The  specific  heat  of  milk 
is,  according  to  Fjord,  0.94;  the  specific  heat  of  cream  is 
about  0.7,  depending  upon  the  percentage  of  fat  it  con- 
tains. Rich  cream  has  a  lower  specific  heat  than  poor 
cream. 

The  maximum  density  of  milk  is  not,  like  water,  at 
4°  C.  (39.2°  F.),  but  at  about  32.9°  F.  The  boiling  point 
is  a  trifle  higher,  and  the  freezing  point  a  trifle  lower  than 
that  of  water. 

Composition  of  Milk.  —  Probably  no  other  food  found 
in  nature,  except  meat,  is  subject  to  such  great  variation 
in  composition  as  is  milk.  The  average  composition  of 
American  milk,  according  to  Babcock,1  is: 

Water 87.17 

Fat 3.69 

Casein 3 . 02 

Albumen .53 

Sugar 4.88 

Ash s  .71 

The  milk  of  individual  animals  varies  from  day  to  day, 
and  varies  as  the  period  of  lactation  advances.  However, 
the  mixed  milk  from  a  large  herd  is  not  subject  to  very 
great  variations,  but  the  milk  of  one  herd  may  differ  greatly 
from  that  of  another  herd,  due  to  the  breed  of  the  cattle. 
The  constituents  subject  to  the  greatest  variation  are  the 
fat  and  casein.  The  following  table2  shows  this: 

1  Farrington  and  Woll  —  Testing  Milk  and  Its  Products. 

2  Van  Slyke  —  Science  and  Practice  of  Cheese  Making. 


DAIRY  TECHNOLOGY 


Breed. 

Per  cent 
fat. 

Per  cent 
casein. 

Per  cent 

total  solids. 

Holstein 

3    26 

2    2O 

II    80 

Ayrshire 

3    76 

2   46 

127=; 

Shorthorn 

4   28 

2    70 

14  30 

Devon 

4.8o 

3  .  IO 

U.  ^o 

Guernsey.    .        

5.38 

2  .QI 

14.90 

Jersey  . 

5.78 

3-O3 

15.40 

Milk  from  one  dealer  may  contain  25  per  cent  to  40 
per  cent  more  nutrients  than  milk  from  another  dealer, 
but  in  the  same  locality  the  consumer  usually  pays  the 
same  price  for  both. 


CHAPTER   II. 

NORMAL  MILK  AND  ITS  PRODUCTS  AS  FOOD. 

FOOD  is  any  substance  taken  into  and  used  in  the  body 
for  the  purpose  of  building  new  tissues  and  repairing  the 
old,  and  for  supplying  the  body  with  heat  and  energy. 
The  best  foods  are  those  which  produce  the  best  physio- 
logical results  with  the  least  amount  of  waste.  They 
must  be  hygienic,  digestible,  palatable,  furnish  the  nu- 
trients needed  by  the  system  in  proper  amounts  and  be 
reasonably  cheap. 

Milk,  properly  produced,  is  a  food  having  all  these 
requirements. 

There  are  three  chief  classes  of  nutrients  necessary  to 
maintain  the  human  body: 

1.  Fats,  sugars,  starches  and  cellulose.     These  are  the 
chief  food  elements  that  produce  energy,  fat  and  heat  in 
the  body.     Cellulose  and  starch  are  not  found  in  milk. 
The  sugar  and  fat  are  the  most  important  ones.    They 
are  found  in  milk  in  sufficient  and  proper  quantities  to 
supply  the  body. 

2.  Proteids.    These  chiefly  produce  the  muscles,  tendons 
and  hair.     They  are  also   to  some  extent  producers  of 
energy.     Good  examples  of  the  proteid  group  are  casein 
and  albumen  found  in  milk. 

3.  Mineral  foods.     The  chief  of  these  are  phosphates, 
chlorides  and  other  salts,  calcium,  potash  and  soda,  with 
small  quantities  of  iron  and  magnesia.    They  chiefly  pro- 
duce the  bones  of  the  body. 

5 


6  DAIRY  TECHNOLOGY 

Milk  contains  iron  and  phosphorus  in  sufficient  quan- 
tities to  supply  the  needs  of  a  growing  individual.  These 
minerals  are  specially  needed  during  the  period  of  cell 
and  tissue  building,  the  nucleus  of  the  body  cell  being  rich 
in  iron  and  phosphorus. 

The  water  in  milk  is  also  essential  to  the  body.  Milk 
contains  enough  water  to  supply  the  body,  providing  the 
body  is  at  rest  and  no  dry  food  other  than  milk  is  con- 
sumed. 

The  nutritive  ratio  of  milk  is  about  i:  4.  While  this 
ratio  is  a  little  narrow,  the  proportion  of  the  different  com- 
ponents is  nearer  perfect  than  in  any  other  single  food. 

Pure,  sweet  and  wholesome  milk  as  a  food  is  preferred 
to  any  other  natural  food,  that  is,  food  not  prepared  by 
man.  Originally  the  milk  from  cows  was  utilized  solely 
for  their  young.  Owing  to  man's  skill  in  selecting  and 
breeding,  the  qualities  of  dairy  cows  and  their  products 
have  been  regulated  and  developed  to  such  an  extent  that 
the  cow's  milk  serves  in  a  large  measure  as  a  food  for  man. 
The  specialized  dairy  types  produce  large  quantities  of 
milk,  and  the  richness  of  the  milk  can  be  regulated  by 
making  the  proper  selection  of  cows. 

Milk  cannot  be  said  to  be  a  perfect  food  for  adults,  be- 
cause, in  the  first  place,  milk  contains  too  large  a  per  cent 
of  water.  As  a  consequence,  too  much  bulk  (8  to  n  Ibs. 
daily)  would  have  to  be  consumed  to  obtain  the  necessary 
nutrients.  Secondly,  there  is  a  trifle  too  large  a  percentage 
of  protein  in  milk  in  proportion  to  the  fat  and  carbohy- 
drates (1:4).  Thirdly,  the  milk  nutrients,  not  including 
water,  are  too  concentrated  or  condensed.  A  certain 
amount  of  bulky  food  is  generally  admitted  to  be  necessary 
to  the  best  digestion  and  health  of  a  person  or  animal. 
Fourthly,  a  digestive  system,  receiving  no  other  food  than 


NORMAL  MILK  AND  ITS  PRODUCTS  AS  FOOD  7 

milk,  is  eventually  likely  to  lack  in  development,  because 
of  being  unaccustomed  to  handle  other  foods,  digested 
with  greater  difficulty;  just  as  the  muscles  of  an  idle 
person,  or  one  who  does  little  work,  are  likely  to  become 
soft  and  weak.  Milk  as  a  food  for  adults  is  most  effective 
when  used  in  conjunction  with  other  foods. 

The  present  extensive  and  increasing  use  of  milk  as  a 
food  is  due  chiefly  to  five  things: 

1.  Fresh   milk,   properly  produced   and   handled,   is 

palatable  and  relished  by  most  people. 

2.  All  the  chief  classes  of  nutrients  (proteids,  carbo- 

hydrates and  fats,  and  minerals)  necessary  for  the 
development  of  the  animal  and  human  body  are 
present  in  such  proportions  as  to  render  milk  most 
serviceable  as  a  food. 

3.  The  food  constituents  are  present  in  milk  in  such 

form  as  to  make  them  easily  digestible. 

4.  Milk  is  a  cheap  food. 

5.  Milk  is  a  food  already  prepared  by  nature. 

Palatability  of  Cows'  Milk.  —  The  palatability  of  milk 
is  due  to  the  fact  that  the  different  components  of  milk 
are  present  in  such  a  proportion  as  to  produce  a  flavor 
suitable  to  the  majority  of  people.  It  is  a  general  principle, 
that  the  more  volatile  and  soluble  a  substance  is,  the  more 
easily  it  can  be  detected  by  the  senses  of  taste  and  smell. 
Some  of  the  natural  flavoring  substances  in  milk,  though 
present  in  very  small  quantities,  are  volatile  and  soluble 
at  a  low  temperature,  so  that  when  warmed  in  the  mouth 
the  flavor  is  quickly  detected.  Milk,  in  order  to  have  its 
best  flavor,  should  be  produced  from  healthy  cows,  fed  on 
food  that  will  impart  the  best  flavors,  such  as  well-cured, 
good,  sweet  hay,  grain,  ensilage  or  roots  in  winter,  and 


8  DAIRY  TECHNOLOGY 

grass  in  summer.  Milk  is  best  for  direct  consumption  as 
soon  as  possible  after  it  is  drawn  and  cooled.  In  case 
of  specially  fermented  milks  this  does  not  apply.  On 
standing,  milk  undergoes  fermentation  and  decomposi- 
tion. The  extent  to  which  these  changes  occur  depends 
upon  the  temperature  at  which  milk  is  kept  and  upon  the 
number  and  kinds  of  germs  in  the  milk.  If  milk  and  other 
dairy  products  are  kept,  they  should  be  held  at  a  low  tem- 
perature. Unpalatable  and  other '  abnormal  milk  will  be 
mentioned  later. 

Digestibility  of  Milk.  -  Milk,  generally  speaking,  ranks 
high  as  a  digestible  food;  but  in  this  connection  it  should 
be  stated  that  the  digestibility  of  cows'  milk  varies.  First, 
it  varies  according  to  the  condition  of  the  milk  (whether 
fresh  or  old,  whether  adulterated  or  not),  and  according 
to  the  composition  of  the  milk.  Secondly,  the  digestibility 
of  milk  varies  according  to  the  power  of  digestion  of  differ- 
ent persons.  Thirdly,  its  digestibility  varies  according  to 
the  amount  consumed,  and  whether  it  is  taken  with  other 
foods  or  not. 

When  milk  is  consumed,  it  passes  first  into  the  stomach, 
where  the  acid  and  pepsin  in  the  gastric  juice  curdle  and 
dissolve  it.  When  milk  is  consumed  in  large  quantities 
at  a  time,  without  the  addition  of  any  other  food,  the  curd 
or  casein  may  gather  in  lumps.  In  this  condition  the  gas- 
tric juice  digests  it  with  difficulty.  Abnormal  fermentation 
may  set  in  and  cause  sickness  before  the  digestive  juices 
have  a  chance  to  bring  the  normal  digestive  changes  about. 
This  condition  is  especially  common  with  infants  and  with 
adults  having  a  weak  digestive  system. 

Human  milk  curdles  differently  from  cows'  milk.  The 
former  contains  less  casein  than  the  latter,  and  the  casein 
is  probably  combined  with  the  mineral  salts  in  a  different 


NORMAL  MILK  AND  ITS  PRODUCTS  AS  FOOD  9 

manner.  The  casein  of  human  milk  is  separated  and  more 
flocculent  when  curdled.  In  this  condition  the  digestive 
juices  attack  it  with  greater  ease. 

Pasteurized  cows'  milk  coagulates  into  a  more  flocculent 
or  separated  curd  than  does  raw  milk. 

Raw  vs.  Heated  Milk.  —  The  effect  of  heat  upon  the 
digestibility  of  milk  is  a  matter  that  the  best  authori- 
ties do  not  agree  upon,  though  it  has  been  the  subject  of 
considerable  investigation.  Heating  milk  to  a  temperature 
sufficiently  high  for  efficient  pasteurization  partly  renders 
the  calcium  salts  insoluble  and  may  partly  coagulate  the 
lactalbumin.  But  since  investigators  obtain  different 
results  in  their  work,  it  seems  evident  that  the  ease  of 
digestibility  of  heated  milk  cannot  differ  greatly  from  that 
of  raw  milk.  And,  as  will  be  shown  later,  the  pasteur- 
ization of  average  city  milk  is  beneficial. 

Use  of  Milk  with  Other  Foods.  —  In  a  series  of  digestion 
experiments  conducted  by  Professor  Harry  Snyder  at  the 
Minnesota  Experiment  Station,  various  foods  were  used 
at  different  times,  milk  constituting  in  many  cases  a  con- 
siderable part  of  the  diet.  One  fact  of  great  practical 
importance  brought  out  by  this  work  was  that  the  various 
foods  showed  a  higher  digestibility  when  milk  was  included 
in  the  diet  than  when  fed  alone. 

The  food  components  may  undergo  many  different 
changes  in  the  digestive  tract,  depending  upon  the  person 
and  the  conditions  and  demands  of  the  person's  system. 
The  complex  cleavage  and  synthetic  changes  of  digestion 
and  assimilation,  especially  during  the  end  processes,  are 
imperfectly  understood. 

When  the  digestibility  of  the  components  of  milk  is 
compared  with  that  of  other  food  substances,  milk  ranks 
among  the  most  digestible  of  all  foods. 


10  DAIRY  TECHNOLOGY 

According  to  experiments,  cows'  milk  contains  3.6  per 
cent  proteid,  of  which  3.48  per  cent  is  digestible.  It  con- 
tains 4.9  per  cent  carbohydrates,  of  which  4.7  per  cent  is 
digestible.  It  contains  3.7  per  cent  fat,  of  which  3.7  per 
cent  is  digestible. 

Relative  Cost  of  Milk.  —  The  place  of  milk  in  the  diet, 
its  use  as  a  substitute  for  other  foods  and  the  relative  value 
of  the  nutrients  it  contains,  as  compared  with  the  cost  of 
nutrients  in  other  foods,  are  not  generally  realized.  Some 
investigations  were  made  at  the  University  of  Maine,1 
in  which  the  effect  of  quantities  of  milk  was  tried  at  the 
university  boarding  house.  From  this  investigation  the 
following  conclusions  were  drawn :  i .  An  abundant  supply 
of  milk  in  the  dietary  decreased  the  cost  without  decreasing 
the  acceptability  of  it  to  the  consumer.  2.  The  increased 
consumption  of  milk  increased  the  proportion  of  protein 
in  the  diet.  3.  The  consumption  of  large  quantities  of 
milk  was  accompanied  by  a  decreased  consumption  of 
other  foods.  4.  Milk  is  not  a  luxury  but  an  economical 
food  that  might  be  more  widely  used  as  a  means  of  im- 
proving the  character  of  the  diet  and  of  reducing  the  cost 
of  animal  foods. 

One  quart  of  milk  (2  Ibs.),  and  three  quarters  of  a  pound 
of  moderately  fat  beef,  such  as  sirloin,  contain  about  the 
same  food  value,2  but  we  pay  different  prices  for  them. 
Milk  is  the  cheaper  and  comes  the  nearer  to  being  a  per- 
fect food.  One  might  live  on  beef  alone,  but  it  would 
be  a  one-sided  diet,  while  milk  is  more  nearly  a  balanced 
ration. 

1  U.  S.  Dept.  of  Agr.,  Office  of  Exp.  Sta.  Bui.  37. 

2  U.  S.  Dept.  of  Agr.,  Farmers'  Bui.  No.  23. 


NORMAL  MILK  AND  ITS  PRODUCTS  AS  FOOD 


II 


TABLE  WHICH   SHOWS  AMOUNTS  OF   NUTRIENTS  IN   A 

POUND  OF  MILK  AS  COMPARED  WITH  A  POUND  OF 

MEAT,  BREAD  AND  OTHER  FOOD  PRODUCTS.1 


Food  materials. 

Refuse. 

Edible  portion. 

Fuel 

value. 

Nutrients. 

Water. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Mineral 
matter. 

Milk  (i  pint  or  i  pound)  : 
Whole  milk  •  
Skim  milk  (0.3  per  cent 
fat)  

Lbs. 

Lb. 

0.87 

0.90 
0.91 

0.34 

O.II 

0.61 
0.69 
0.53 
0.50 
0.51 
0.43 

0.44 
0-35 
0.07 
0.48 

0.58 
0.40 
0.38 
0.88 

0.12 

0.13 
0.07 
0.35 
0.08 
0.13 
o  70 

Lb. 
0.03 

0.04 
0.03 

0.26 

O.OI 

0.18 
0.19 
0.16 
0.14 
0.15 
0.13 

0.14 
0.13 

O.O2 
0.15 

O.II 

0.16 

0.17 
0.06 

O.II 

0.09 
0.16 

O.IO 
O.II 
0.22 
O  OI 

Lb. 

0.04 

O.OI 

0.34 
0.85 

O.I2 
O.II 

0.17 
0.16 
0.17 
0.24 

0.25 
0.34 
0.87 

O.OI 

0.17 

O.O2 
O.OI 
O.O2 
0.07 
O.OI 
O.IO 
0.02 

Lb. 
0.05 

0.05 
0.05 

O.02 
0.03 

0.75 
0.75 
0.68 
0.53 
0.69 
0.59 
0.08 

0.06 
O.I2 

Lb. 

O.OI 

O.OI 
O.OI 

0.04 
0.03 

O.OI 
O.OI 
O.OI 
O.CI 
O.OI 
O.OI 

O.OI 

0.04 
0.04 

O.OI 
O.OI 

0.19 

O.IO 
O.OI 
O.OI 
O.OI 
O.O2 
O.OI 
0.02 

0.04 

O.OI 
O.OI 
O.OI 

Cal. 
325 

170 
165 

1965 
3605 

870 
835 
1040 
95o 

1000 

1275 

1340 
1655 
3715 
325 

205 
315 
1050 
235 
1645 
1655 
1860 
1205 
1895 
1590 
170 
325 
135 
255 

Buttermilk  
Other    food    materials     (i 
pound  each): 
Cheese 

Butter.  .  . 

Beef: 
,;  Round  
Shoulder  clod 

0.08 

0.13 
0.19 
0.16 
0.19 

0.16 
0.14 

Sirloin  

Fore  quarters  
Hind  quarters  

Mutton,  side  
Pork: 
Loin  
Ham  . 

Salt,  fat  

Chicken.                      .   . 

0.35 

0.30 
0.25 
0.23 

Codfish: 
Fresh                          .    . 

Salt 

Mackerel,  salt  

Wheat  flour  
Corn  meal  .  . 

Oatmeal  
Wheat  bread 

Crackers  
Dried  beans  
Beets 

o  20 

Potatoes  
Turnips  

0.15 
0.30 
0.25 

0.67 
0.62 
0.62 

O.O2 
O.OI 
O.OI 

Apples  

1  U.  S.  Dept.  of  Agr.,  Farmers'  Bui.  No.  74. 


12 


DAIRY  TECHNOLOGY 


TABLE  WHICH  SHOWS  NUTRIENTS  AND  ENERGY  IN  ONE 

POUND  OF  THE  WATER-FREE  EDIBLE   PORTION 

OF   SEVERAL  FOOD  MATERIALS.1 


Food  materials. 

Protein. 

Fat. 

Carbo- 
hydrates. 

Mineral 
matter. 

Fuel  value. 

Lb. 

Lb. 

Lb. 

Lb. 

Cal.i 

Whole  milk  

0.25 

0.31 

0-39 

0.05 

2475 

Skim    milk     (0.3 

per  cent  fat)  .... 

0.36 

0.03 

o-55 

O.o6 

1835 

Buttermilk  

0-33 

O.o6 

o-53 

O.o8 

1845 

Cheese  

0-39 

0.52 

0.03 

O.o6 

2990 

Beef,  round  

0-57 

0.40 

0.03 

2750 

Smoked  ham  

0.26 

0.66 

0.08 

3275 

Wheat  flour  

0.13 

O.OI 

0.85 

O.OI 

1865 

Wheat  bread  

°-*S 

O.O2 

0.82 

O.OI 

1865 

Potatoes  

o.  10 

O.OI 

0.85 

0.04 

1790 

Apples 

o  03 

o  03 

O    Q2 

O.O2 

1881? 

w  •  wo 

w  •  wo 

v  •  V 

uu^ 

1  One  calorie  is  the  amount  of  heat  necessary  to  raise  the  temperature  of  one  pound 
of  water  4°  F.  or  i  kilogram  of  water  i°  C. 

The  cheapest  food  is  that  which  furnishes  the  largest 
amount  of  digestible  and  healthful  nutrients  at  the  least 
cost.  The  cost  of  one  pound  of  round  steak  is  about  twelve 
cents;  of  one  pound  of  sirloin  about  fifteen  cents;  and  of 
one  pound  of  milk  about  two  and  one  half  cents.  In  price 
five  pounds  of  milk  is  equal  to  one  pound  of  round  steak, 
and  six  pounds  is  equal  to  one  pound  of  sirloin  steak. 


1  U.  S.  Dept.  of  Agr.,  Farmers'  Bui.  No.  74. 


NORMAL  MILK  AND  ITS  PRODUCTS  AS  FOOD 


APPROXIMATE  COST  OF  NUTRIENTS  IN  MILK  AS 
COMPARED  WITH   OTHER  FOOD  MATERIALS.1 


Food  materials. 

Whole  milk. 

Skim  milk. 

Amount. 

Cost  at 
6  cents 
per  qt. 

Amount. 

Cost  at 
3  cents 
per  qt. 

One  pound  of  beef: 
Round  furnishes  protein  equivalent  to 

Quarts. 

2.7 
1.3 

2.9 
1.2 

2.4 

1.6 

2.0 
2.2 

2.1 
2.1 
2.3 
5-7 
2.0 
2.5 
2.2 
0.5 

2.4 
0.5 
1.9 
0.4 
1.7, 

2.5 
1.4 
1.9 
33 
2.4 
0.3 
o.S 

0.2 
O.2 

Cents. 

16 
8 
I? 

7 
14 

10 
12 

13 

13 
13 

2 
34 

12 

15 
13 
3 
14 
3 
II 

2 
10 

IS 
8 
II 
20 

14 

2 
3 
I 

I 

Quarts. 
2.7 

2.6 

2.9 

2.5 

2.4 

32 

2.0 
4-4 

2.1 
4-1 
03 
II.  3 

.0 
.0 

.2 
0 

.4 

.0 

.9 
.  7 
-7 
-o 
.4 
•  7 
•  3 
.8 
•  3 

.0 
0.2 

0.4 

Cents. 

8 
8 
9 

7 
7 

10 

6 
13 

6 

12 
I 
34 
6 
15 
7 
3 
7 
3 
6 
2 
5 
15 
4 
ii 

10 

14 

I 
3 

I 

Round  furnishes  fuel  value  equivalent  to  
Shoulder  clod  furnishes  protein  equivalent  to  ... 
Shoulder  clod  furnishes  fuel  value  equivalent  to  . 
Sirloin  furnishes  protein  equivalent  to  

Mutton  loin  furnishes  protein  equivalent  to  
Mutton  loin  furnishes  fuel  value  equal  to  

Pork: 

Fresh,  furnishes  protein  equivalent  to  
Fresh   furnishes  fuel  value  equal  to   ... 

Salt,  fat,  furnishes  protein  equal  to  
Salt,  fat,  furnishes  fuel  value  equal  to  
Smoked  ham  furnishes  protein  equal  to  
Smoked  ham  furnishes  fuel  value  equal  to  
Chicken  furnishes  protein  equal  to  

Chicken  furnishes  fuel  value  equal  to  
Salt  cod  furnishes  protein  equal  to 

Salt  cod  furnishes  fuel  value  equal  to  
Oysters   "  solid  "  furnish  protein  equal  to 

Oysters,  "  solid,"  furnish  fuel  value  equal  to  
Wheat  flour  furnishes  protein  equal  to  .  . 

Wheat  flour  furnishes  fuel  value  equal  to  
Wheat  bread  furnishes  protein  equal  to.  :  
Wheat  bread  furnishes  fuel  value  equal  to  
Beans,  dried,  furnish  protein  equal  to  
Beans  dried,  furnish  fuel  value  equal  to 

Potatoes  furnish  protein  equal  to  
Potatoes  furnish  fuel  value  equal  to 

Turnips  furnish  protein  equal  to  

Turnips  furnish  fuel  value  equal  to 

5  pounds  of  milk  worth  12  cents  have  a  total  fuel  value 
of  1625  calories. 

i  pound  of  round  steak  worth  12  cents  has  a  total  fuel 
value  of  855  calories. 

i  pound  of  sirloin  steak  worth  12  cents  has  a  total  fuel 
value  of  970  calories. 

4|  pounds  of  wheat  flour  worth  12  cents  have  a  total 
fuel  value  of  7896  calories. 

1  U.  S.  Dept.  of  Agr.,  Farmers'  BuL  No.  74. 


14  DAIRY  TECHNOLOGY 

3  pounds  of  wheat  bread  worth  12  cents  have  a  total 
fuel  value  of  3840  calories. 

9f  pounds  of  potatoes  worth  12  cents  have  a  total  fuel 
value  of  3600  calories. 

2f  pounds  of  beans  worth  12  cents  have  a  total  fuel  value 
of  3876  calories. 

The  prices  of  the  different  foods  mentioned  above  vary. 
The  prices  prevailing  in  this  section  of  the  country  have 
been  used  in  making  the  above  comparison. 

From  the  above  statement  it  will  be  seen  that  the  food 
value  of  milk  is  much  greater  than  that  of  beef  when  the 
price  of  each  is  taken  into  consideration.  On  the  other 
hand,  wheat  bread  and  potatoes  are  foods  having  a  high 
fuel  value;  but  both  are  rather  one-sided  rations,  as  may 
be  seen  from  the  preceding  table  giving  the  nutritive 
ratio.  Potatoes  as  an  exclusive  diet  would  be  undesirable 
on  account  of  the  great  quantity  necessary  in  order  to  get 
the  required  number  of  calories.  From  the  analysis  of 
beans,  it  will  be  seen  that  they  form  a  very  narrow  ration, 
but  when  eaten  with  some  fatty  food,  they  are  cheap. 

Fresh,  normal  milk  is  a  healthful,  palatable,  cheap 
and  easily  digested  food.  It  is  owing  to  this  that  the 
demand  for  milk  is  constantly  on  the  increase.  With  the 
increased  production  of  milk  for  direct  consumption  in 
cities,  great  care  has  been  exercised,  and  must  be,  in  order 
to  get  the  milk  into  the  market  in  good  condition. 

"  If  the  American  people  would  eat  half  less  meat  and 
consume  one  half  more  milk,  they  would  save  about  one 
hundred  and  fifty  millions  of  dollars  in  money,  and,  in 
health,  enough  to  make  the  doctors'  bills  look  small."  1 

Skim  milk.  —  The  value  of  skim  milk  depends  to  a  certain 
extent  upon  the  method  employed  in  separating  the  cream. 
1  Storrs  —  Conn.  Bui.  No.  51. 


NORMAL  MILK  AND   ITS  PRODUCTS  AS  FOOD         15 

The  method  of  separation  affects  the  age  of  the  skim  milk 
and  the  per  cent  fat  remaining  in  the  skim  milk. 

The  shallow  pan  gravity  system  of  creaming  leaves 
from  0.3  per  cent  to  0.5  per  cent  fat  in  the  skim  milk.  This 
method  requires  about  thirty-six  hours  for  the  cream  to 
rise.  During  this  time  the  temperature  of  the  milk  is 
about  60°  F.,  and  in  some  instances  higher.  These  con- 
ditions, although  favorable  for  a  high  per  cent  of  fat,  are 
not  conducive  to  the  best  quality  of  skim  milk,  as  the 
various  ferments  are  more  or  less  active  at  the  above- 
mentioned  temperature. 

The  "  Cooley  "  or  deep  setting  system  of  creaming  pro- 
duces skim  milk  which  contains  about  0.2  per  cent  to  0.4 
per  cent  fat.  The  cream  rises  in  about  twenty-four  hours, 
and  during  this  time  it  is  kept  at  from  40°  to  50°  F.  This 
temperature  is  so  low  that  the  ferments  have  little  or  no 
deleterious  effect  on  the  quality  of  the  skim  milk. 

The  skim  milk  obtained  by  the  water-dilution  method 
of  separation  will  not  be  considered  in  this  connec- 
tion. 

Most  of  the  dairy  farmers  in  the  central  west  now  have 
hand  separators,  which  do  more  efficient  skimming  than 
can  be  accomplished  by  any  of  the  gravity  systems.  The 
skim  milk  obtained  by  the  centrifugal  method,  under  ideal 
conditions,  does  not  contain  more  than  o.i  per  cent  butter 
fat.  The  machines,  however,  are  seldom  operated  under 
ideal  conditions,  and  the  milk  is  not  always  skimmed  under 
conditions  most  conducive  to  the  complete  removal  of  the 
fat.  Tests  and  observations  by  the  authors  warrant  the 
statement  that  skim  milk  from  hand  separators  on  the  farm, 
on  an  average,  contains  about  0.2  per  cent  fat.  This 
skim  milk  is  fresh,  and  many  of  the  impurities  and  germs 
have  been  removed  in  the  process  of  separation.  Fresh 


l6  DAIRY  TECHNOLOGY 

skim  milk  obtained  in  this  manner  is  healthful  and  nutri- 
tious.   The  average  composition  of  centrifugal  skim  milk  is  :x 

Per  cent. 

Water 90. 25 

Fat o .  20 

Casein  and  albumen 3 . 60 

Milk  sugar 5.15 

Ash o .  80 

Skim  milk  may  be  used  profitably  as  a  food  more  ex- 
tensively than  it  is,  both  in  the  kitchen,  as  an  ingredient 
in  cooked  foods,  and  for  direct  use,  as  a  drink.  When  the 
butter  fat  is  removed,  the  percentage  of  the  other  milk 
components  is  slightly  increased.  The  protein,  sugar, 
minerals  and  some  fat  are  still  left.  These  constitute 
some  of  the  most  valuable  nutrients  of  milk. 

In  some  of  the  older  countries  of  Europe,  skim  milk  is 
used  daily  in  the  kitchen.  Gruels,  puddings,  gravies  and 
soups  are  made  by  using  skim  milk  instead  of  water. 
White  bread  dough  is  made  from  skim  milk.  Skim  milk 
is  also  used  very  extensively  as  a  drink  in  connection  with 
lunches.  Machines  have  been  made  and  set  out  on  the 
corners  of  the  streets  and  other  public  places  where  a 
person  may  obtain  a  glass  of  milk  by  dropping  a  coin  in 
the  slot.  Such  machines  are  not  at  all  common.  When 
used,  great  care  is  necessary  to  keep  the  milk  in  good  con- 
dition and  to  keep  the  apparatus  sanitary. 

Skim  milk,  together  with  bread,  furnishes  a  cheap,  health- 
ful and  nutritious  lunch.  It  is  generally  assumed  that  an 
average-sized  man  doing  average  manual  work  requires 
0.28  pound  of  protein  and  enough  of  the  other  food  con- 
stituents to  make  a  total  fuel  value  of  3500  calories  per 
day.2 

1  Snyder  —  Dairy  Chemistry. 

2  U.  S.  Dept.  of  Agr.,  Farmers'  Bui.  No.  74. 


NORMAL   MILK  AND   ITS   PRODUCTS   AS   FOOD 


The  following  meal  of  bread  and  milk  furnishes  nearly 
one  third  the  nutrients  required  by  a  man  per  day.1 


Protein. 

Pat. 

Carbo- 
hydrates. 

Mineral 

matter. 

Fuel 
value. 

Esti- 
mated 
cost. 

(|  Lb.)  10  oz.  of 
wheat  bread, 
(i  Lb.)  i  pt.  of 
skim  milk.  .  . 
Total  

Lb. 
0.062 

0.040 
O.  IO2 

Lb. 
0.0062 

o  .  0030 
0.0092 

Lb. 

0-33 

0.05 

0.38 

Lb. 
0.0062 

0.0070 
0.0132 

Cals. 

753 

i75 
928 

Cents. 

3 

I 
4 

A  woman  and  a  boy  between  14  and  16  years  of  age 
require  about  0.8  the  food  of  a  man. 

A  girl  14  to  1 6  years  old  requires  about  0.7  the  food  of 
a  man. 

A  child  10  to  13  years  old  requires  about  0.6  the  food 
of  a  man. 

A  child  6  to  9  years  old  requires  about  0.5  the  food  of 
a  man. 

A  child  3  to  5  years  old  requires  about  0.4  the  food  of 
a  man. 

A  child  under  2  years  old  requires  about  0.3  the  food  of 
a  man. 

Buttermilk.  —  Buttermilk  is  an  important  dairy  by- 
product. As  most  of  the  butter  is  made  at  creameries  or 
at  central  points  the  bulk  of  the  buttermilk  is  produced 
at  central  places,  where  the  supply  is  greater  than  the  de- 
mand. As  a  consequence,  a  large  portion  of  it  is  not  utilized 
at  all. 

Buttermilk  has,  practically  speaking,  the  same  food 
value  as  skim  milk,  if  during  the  manufacturing  processes 
the  buttermilk  has  not  been  adulterated.  It  contains 
from  0.4  to  0.8  per  cent  lactic  acid,  according  to  age  and 
degree  of  ripening  of  the  cream.  This  acid  is  produced 
1  U.  S.  Dept.  of  Agr.,  Farmers'  Bui.  No.  74. 


1 8  DAIRY  TECHNOLOGY 

through  fermentation.  About  one  per  cent  of  sugar  is 
required  to  produce  the  amount  of  lactic  acid  mentioned 
above.  In  this  change  of  milk  sugar  to  lactic  acid,  other 
by-products  are  simultaneously  produced.  The  complete- 
ness with  which  the  milk  sugar  is  transformed  into  lactic 
acid  depends  upon  the  species  of  germs  present.  Butter- 
milk then  contains  more  acid  and  less  sugar  than  skim 
milk. 

It  is  also  claimed  that  the  casein  in  buttermilk  is  easier 
to  digest,  because  it  exists  in  a  more  soluble  form,  being 
partly  combined  with  lactic  acid  in  the  form  of  casein 
lactate. 

Buttermilk  is  used  extensively  as  a  beverage.  When 
the  cream  has  been  properly  ripened,  the  buttermilk  is 
not  only  nutritious  but  it  is  healthful.  Some  physicians 
prescribe  it  for  their  patients.  It  is  widely  believed  that 
it  may  be  used  successfully  as  a  remedy  for  kidney  trouble. 

Buttermilk  is  used  extensively  as  a  food  for  hogs  and 
chickens. 

The  average  composition  of  buttermilk  is : 1 

Per  cent. 

Water 90 . 50 

Fat .- o.  20 

Casein  and  albumen 3  30 

Milk  sugar 5 . 30 

Ash o.  70 

Cream.  —  Cream  is  the  portion  of  milk  containing 
most  of  the  fat.  It  may  be  separated  either  by  gravity 
or  by  a  centrifugal  separator,  and  to  be  legal,  cream  may 
contain  from  18  to  50  per  cent  fat,  and  even  more.  Market 
cream  normally  contains  18  to  25  per  cent  fat.  The  fuel 
value  of  a  pint  of  cream  is  about  1425  calories,  more  than 
four  quarts  of  milk.  However,  cream  is  lacking  in  pro- 

1  Snyder  —  Dairy  Chemistry. 


NORMAL  MILK  AND  ITS  PRODUCTS  AS  FOOD         19 

tein,  and  is  chiefly  valuable  as  a  producer  of  heat  and 
energy,  and  for  this  purpose  it  is  not  so  economical  as 
butter.  On  account  of  its  delicious  flavor  and  high  food 
value,  cream  is  extensively  used,  chiefly  in  connection 
with  other  foods.  Sweet  cream  is  perhaps  relished  by 
more  people  than  is  any  other  one  food. 

The  following  is  a  fair  average  composition  of  cream 
as  found  on  the  markets  of  this  country : 1 

Per  cent. 

Water 66  .41 

Fat 25.72 

Casein  and  albumen 3 . 70 

Milk  sugar 3 . 54 

Ash o.  63 

Butter.  —  Butter  is  one  of  the  most  important  sources 
of  fat  in  our  diet,  one  of  the  most  palatable  and  easily 
digested.  According  to  recent  statistics,  butter  consti- 
tutes about  two  per  cent  of  the  total  food,  and  furnishes 
19.7  per  cent  of  the  total  fat  in  the  average  American  diet. 
Its  flavor  depends  more  upon  the  fermentation  and  chemi- 
cal changes  that  have  taken  place  in  the  cream  before 
churning  than  upon  the  fat  itself.  However,  butyrin, 
the  characteristic  fat  of  butter,  imparts  to  good  butter  a 
peculiar  and  desirable  flavor  that  cannot  be  imitated  by 
any  other  substance.  In  old  or  highly  salted  butter,  this 
delicate  flavor  is  replaced  by  the  stronger  and  undesirable 
flavors. 

The  price  of  butter  is  not  necessarily  dependent  upon 
its  food  value,  but  upon  supply  and  demand,  and  upon 
its  flavor  and  appearance.  The  best  grade  of  butter  fre- 
quently sells  for  50  per  cent  more  than  the  lowest  grade. 

The  coefficient  of  digestion  of  butter  is  about  ninety- 
nine.  This  is  higher  than  other  animal  fats,  the  latter 

1  Snyder  —  Dairy  Chemistry. 


20  DAIRY  TECHNOLOGY 

being  about  95  per  cent  digestible.  Butter  is  made  up 
of  a  relatively  large  percentage  of  fats  having  a  low  melt- 
ing point.  Butter  has  a  melting  point  of  about  33°  C. 
(91. 4°  F.),  while  the  fats  of  beef  and  mutton  melt  at  40° 
to  45°  C.  (109°  F.),  higher  than  the  body  temperature  of 
man.  Butter-fat  globules  are  very  minute  in  size,  and 
hence  are  readily  emulsified,  digested  and  absorbed.  Be- 
cause of  its  low  melting  point  and  its  physical  condition, 
butter  is  more  easily  digested  than  other  animal  fats. 

As  much  as  a  quarter  of  a  pound  of  butter  per  day  has 
been  consumed  by  an  individual  and  found  to  be  readily 
absorbed.  It  is  recommended  by  some  physicians  as  a 
tonic  instead  of  cod  liver  oil  or  similar  preparations. 

Composition  of  Butter: 1 

Per  cent. 

Fat 82.97 

Water 13 . 78 

Proteids o.  84 

Milk  sugar o- 39 

Ash o.  16 

Salt i .  86 

Cheddar  Cheese.  —  Cheese  is  a  concentrated  form  of 
certain  constituents  of  milk,  and  hence  has  a  high  food 
value.  It  is  a  very  concentrated  food  and  gives  best  re- 
sults when  used  in  combination  with  other  and  more  bulky 
foods.  A  large  number  of  experiments  carried  on  by  the 
Office  of  Experiment  Stations  in  cooperation  with  the 
Bureau  of  Animal  Industry  of  the  Department  of  Agri- 
culture has  shown  that,  when  consumed  even  in  relatively 
large  amounts,  cheese  is  very  thoroughly  digested  and 
assimilated.  The  cheaper  varieties  of  cheese  usually 
contain  as  much  food  value  as  the  higher  priced  kinds. 

1  Storch  —  Richmond's  Dairy  Chemistry. 


NORMAL  MILK  AND  ITS  PRODUCTS  AS  FOOD         21 

Nutrients  may,  therefore,  be  supplied  at  a  less  cost  by  using 
cheeses,  such  as  Cottage  and  Cheddar  (American),  than 
by  buying  the  fancy  and  imported  varieties. 

From  the  standpoint  of  the  protein  content  alone, 
two  thirds  of  a  pound  of  cheese  has  the  same  food  value 
as  one  pound  of  beefsteak.  The  fuel  value  of  cheese  is 
nearly  twice  that  of  beef.  As  much  as  a  half  pound  of 
cheese  per  day  may  be  used  in  the  diet  without  any  physi- 
ological disturbances. 

Composition  of  Cheddar  Cheese : 1 

Per  cent. 

Water 36 . 84 

Protein 23 . 72 

Fat 33.83 

Ash,  etc 5.61 

Cottage  Cheese.  —  This  product  of  the  dairy,  known 
also  by  the  names  "  Dutch  Cheese  "  and  "  Schmier  Kase," 
should  have  a  more  prominent  place  in  our  diet. 

Professor  Snyder  of  the  University  of  Minnesota  fed 
several  farm  laborers  on  the  following  daily  ration:  i.i 
pounds  cottage  cheese,  1.16  pounds  bread,  4.12  pounds 
milk  and  0.06  pound  sugar.  The  cottage  cheese  supplied 
over  40  per  cent  of  the  total  protein  and  about  28  per 
cent  of  the  total  fat  of  the  ration.  This  was  found  to 
be  a  very  satisfactory  ration  from  the  standpoint  of 
digestibility  and  nutritive  value.  On  an  average,  95  per 
cent  of  the  protein  and  fat  and  97  per  cent  of  the  carbo- 
hydrates were  digested,  and  90  per  cent  of  the  energy  was 
available  to  the  body.  These  are  approximately  the  same 
results  as  were  secured  when  milk  furnished  the  major 
portion  of  the  nutrients. 

"  Pound  for  pound,  cottage  cheese  prepared  with  cream 
compares  favorably  in  composition  and  digestibility  with 

1  Van  Slyke  —  Science  and  Practice  of  Cheese  Making. 


22  DAIRY  TECHNOLOGY 

beef  and  other  meats.  One  hundred  pounds  of  skim  milk 
and  4  pounds  of  cream,  containing  20  per  cent  fat,  will 
make  from  15  to  16  pounds  or  more  of  moist  cottage  cheese. 
At  2  cents  per  quart  for  skim  milk  and  35  cents  per  quart 
for  cream,  cottage  cheese  would  cost  about  eleven  cents 
per  pound,  and  compares  very  favorably  in  nutritive 
value  with  meats  at  the  same  price  per  pound.  Where 
skim  milk  can  be  procured  at  a  low  cost,  cottage  cheese 
is  one  of  the  most  economical  foods  that  can  be  used.  The 
addition  of  cream  to  cottage  cheese  favorably  influences 
both  its  nutritive  value  and  its  palatability  without  in- 
creasing the  cost  above  that  of  average  meats.  Upon 
the  farm,  where  milk  is  produced,  cottage  cheese  is  one 
of  the  cheapest  foods  that  can  be  used."1 

The  composition  of  cottage  cheese  varies  greatly,  de- 
pending upon  the  method  of  manufacture,  the  fat  content 
of  the  milk  used,  and  the  addition  of  milk  or  cream  to  the 
curd.  The  following  is  considered  a  fair  average  compo- 
sition of  cottage  cheese  as  commonly  made:2 

Per  cent. 

Water 37.35 

Fat 24.61 

Proteids 32 . 40 

Ash 5 . 65 

1  Minnesota  Bui.  No.  92. 

2  Konig  —  Richmond's  Dairy  Chemistry. 


CHAPTER   III. 

ABNORMAL  MILK. 

ALTHOUGH  milk  is  normally  such  a  desirable  and  ex- 
cellent food,  it  is,  like  other  foods,  subject  to  various 
modifications  and  fermentations,  depending  upon  the  con- 
ditions under  which  it  is  produced  and  subsequently 
handled.  This  abnormality  may  be  merely  a  slightly 
bad  odor  and  flavor  or  it  may  be  some  very  marked  un- 
desirable characteristic  of  color,  consistency,  odor  or  taste. 

Again,  the  milk  may  appear  and  taste  perfectly  normal 
but  at  the  same  time  contain  pathogenic  organisms  or 
toxic  properties  that  may  prove  serious  and  even  fatal 
to  the  consumer. 

Milk  may  acquire  abnormal  flavors  or  odors  in  several 
ways:  The  cow  may  be  slightly  sick  and  produce  milk 
with  an  unusual  flavor.  This  is  usually  temporary. 
Highly  flavored  foods  such  as  onions  or  turnips,  when 
eaten  by  the  cow,  may  impart  their  flavor  to  the  milk. 
Milk  absorbs  any  odor  that  it  may  be  exposed  to,  such 
as  zenoleum,  creolin,  or  other  strong-smelling  disinfectants, 
when  used  in  the  barn  too  close  to  milking  time.  Flavor 
of  milk  may  be  altered  after  it  has  been  drawn,  by  growth 
of  bacteria  in  it.  The  commonest  change  is  the  souring  and 
curdling  of  the  milk,  due  to  a  fermentation  of  the  milk 
sugar,  in  which  the  latter  is  broken  down  into  lactic  acid. 
This  is  a  normal  fermentation  and,  though  not  desired  in 
fresh  milk,  is  not  deleterious  to  health. 

Poisonous  Milk.  —  When  cows  eat  leaves  of  the  common 
poison  ivy  (Rhus  toxicodendron)  the  toxic  properties 

23 


24  DAIRY  TECHNOLOGY 

may  be  found  in  the  milk.  Ingestion  of  such  milk  by  a 
human  being  may  cause  severe  gastro-intestinal  trouble. 
Leaves  of  the  common  artichoke  are  also  said  to  produce 
certain  toxic  properties  in  the  milk  which  cause  abdominal 
pains  and  diarrhea  in  the  consumer.  In  a  few  instances, 
milk  sellers  unlawfully  add  preservatives,  such  as  formalin. 

Colored  Milk.  —  Milk  may  have  a  reddish  color  due 
to  the  presence  of  blood  in  the  milk,  or  such  color  may 
be  caused  by  bacterial  growth.  Eating  certain  plants 
may  affect  the  color  of  the  milk.  Bacillus  cyanogenes 
is  known  to  have  infected  dairies  and  caused  a  bluish  dis- 
coloration of  the  milk. 

Bitter  Milk. — Bitter  milk  occasionally  may  be  observed 
during  the  late  stages  of  lactation.  It  may  be  caused  by 
the  cow  eating  lupines,  wormwood,  etc.,  or  it  may  be  the 
result  of  bacterial  growth. 

Stringy  or  Ropy  Milk.  —  Stringy  or  ropy  milk  is  caused 
by  a  growth  of  bacteria  that  are  surrounded  by  a  gummy 
capsule.  So  far  as  known  there  is  nothing  harmful  about 
this  fermentation,  but  milk  of  this  kind  is  very  distasteful 
to  most  people  in  this  country.  Some  foreign  people 
consider  ropy  milk  a  desirable  beverage.  In  some  in- 
stances they  produce  this  condition  by  introducing  into 
the  milk  leaves  of  certain  plants  on  which  bacteria  causing 
milk  to  be  ropy  are  found.  Edam  cheese  is  nearly  all  made 
from  milk  that  has  undergone  this  or  similar  fermentation. 
In  modern  factories  pure  cultures  of  this  particular  fer- 
ment (Bacillus  Hollandicus)  are  propagated. 

Colostrum.  —  This  substance,  although  the  natural 
product  of  the  mammary  glands,  is  not  milk  according 
to  our  pure  food  laws.  We  may,  however,  from  the  stand- 
point of  human  food  call  it  abnormal  milk.  Colostrum 
is  a  yellow,  viscid  fluid  of  abnormal  milk  odor,  and  some- 


ABNORMAL  MILK  25 

what  bitter  taste.  It  is  especially  secreted  as  the  first 
food  for  the  young,  and  is  adapted  only  to  that  purpose. 
The  ingestion  of  such  milk,  especially  by  children,  is  apt 
to  produce  diarrhea,  colic  or  other  digestive  disturbances. 
Some  foreign  people,  however,  after  the  first  two  days, 
use  it  for  cooking  purposes. 

General.  —  Until  a  few  years  ago  little  was  known  about 
tlie  effects  of  bacteria  and  other  germs.  This  very  seri- 
ously interfered  with  the  dairy  industry.  Major  Alvord 
reports  that  in  a  period  from  1815  to  1830,  in  an  agricul- 
tural district  in  Mecklenburg,  Germany,  the  disease  of 
blueness  in  the  milk  lasted  eight  years,  and  that  in  earlier 
times,  in  the  best  agricultural  districts  of  Schleswig-Hol- 
stein,  butter  would  become  cheesy  and  moldy  for  several 
months  in  the  summer.  Such  defects  in  dairy  products 
occur  at  the  present  time,  but  in  intelligent  dairy  circles 
they  last  only  a  short  time,  as  the  causes  of  them  are 
known  and  remedies  can  be  applied. 

We  know  now  that  the  chief  cause  of  these  defects  is 
the  action  of  bacteria  on  the  components  of  milk.  Milk, 
when  first  drawn,  contains  gases  and  animal  odors,  which 
in  a  large  measure  may  be  eliminated  by  cooling  and 
aerating  it  in  a  clean  atmosphere  immediately  after  it 
has  been  drawn.  The  aeration  causes  the  gases  to  pass 
off,  and  the  cooling  keeps  the  milk  in  good  condition  and 
causes,  fermentation  to  be  wholly  or  partly  checked.  Cool- 
ing milk  to  about  50°  F.  and  below  this  temperature 
checks  fermentation  so  that  the  natural  sweet  flavor  of 
the  milk  can  be  preserved  without  other  preservatives 
for  72  hours  or  longer,  providing  all  utensils,  receptacles 
and  surroundings  are  perfectly  clean.  If  not,  the  milk 
will  go  "  off  "  in  flavor.  Milk,  kept  even  at  a  low  tem- 
perature, will  in  time  lose  its  palatability,  owing  to  the 


26  DAIRY  TECHNOLOGY 

many  forms  of  ferments  existing  in  milk  and  to  our  incom- 
plete control  over  the  fermentations. 

Generally  speaking,  milk  properly  produced  and  handled 
does  not  become  abnormal.  When,  in  special  cases, 
abnormal  milk  is  produced,  it  should  be  excluded  from 
the  consuming  channel  and  measures  be  enforced  to  over- 
come the  adverse  conditions. 

J.  H.  Mohler1  describes  the  effect  of  diseased  conditions 
of  cows  upon  the  hygienic  qualities  of  the  milk  secreted. 
He  states  that  any  of  the  following-named  diseases  of  the 
cow  may  seriously  affect  the  milk,  making  milk  from  cows 
afflicted  with  such  diseases  unusable  as  human  food: 
tuberculosis,  foot  and  mouth  disease,  actinomycosis  of 
the  udder,  anthrax,  cow-pox,  rabies,  mammitis  or  garget, 
gastro-enteritis,  or  any  condition  causing  a  great  increase 
in  the  leucocyte  content  of  the  milk. 

1Hygienic  Laboratory,  Bui.  No.  56. 


PART    II. 
CITY    MILK   SUPPLY. 

CHAPTER  IV. 

EXTENT  AND  IMPORTANCE  OF  THIS  INDUSTRY. 

THE  distribution  of  fresh  milk  to  the  consumer  is  an  in- 
dustry of  great  economic  and  hygienic  importance.  Its 
vastness  is  indicated  by  the  following  statistics  gathered 
by  the  United  States  Department  of  Agriculture:  The 
American  people  consume  annually  over  a  billion  gallons 
of  milk  in  its  natural  state,  the  product  of  nearly  one-third 
of  the  milch  cows  in  this  country.  Milk  is  almost  as  neces- 
sary in  cooking  as  flour.  Few  meals  are  served  at  which 
milk  and  cream  do  not  form  a  part.  The  following  table 
shows  the  daily  per  capita  consumption  of  milk  in  1900 
in  the  fifteen  largest  cities  of  the  United  States.1 

Pints. 

New  York,  N.  Y 660 

Chicago,  111 758 

Philadelphia,  Pa 466 

St.  Louis,  Mo 409 

Boston,  Mass 1.172 

Baltimore,  Md ' 393 

Cleveland,  Ohio 482 

Buffalo,  N.  Y 704 

San  Francisco,  Cal 630 

Cincinnati,  Ohio 614 

Pittsburgh,  Pa 746 

New  Orleans,  La 275 

Detroit,  Mich 700 

Milwaukee,  Wis 691 

Washington,  D.  C .344 

1  U.  S.  Dept.  of  Agr.,  Div.  of  Statistics,  Bui.  25. 
27 


28  DAIRY  TECHNOLOGY 

Southern  cities  consume  less  milk  per  capita  than  do 
Northern  cities.  The  following  cities  are  reported  to  have 
a  per  capita  consumption  of  about  one  pint  of  milk  per 
day:  Worcester,  Mass.;  Newton,  Mass.;  Providence, 
R.  L;  Hoboken,  N.  J.;  Minneapolis,  Minn.;  and  Sioux 
City,  la. 

The  increase  in  the  production  of  milk  is  indicated 
by  the  increase  in  the  number  of  dairy  cows,  which  accord- 
ing to  United  States  statistics,  are  as  follows  in  the  United 
States: 

No.  of  cows. 
1870 10, 096,  ooo 

l88o 12,  O27,  OOO 

1890 15,  953,  ooo 

1900 16,  292,  ooo 

1910 21,  801,  ooo 

The  per  capita  consumption  of  milk  is  on  the  increase. 
As  an  illustration  of  this,  let  us  consider  the  milk  and  cream 
supply  of  New  York  City  for  the  past  25  years. 

Gallons. 

1885 51,  026, 660 

1890 64, 801,  190 

1895 80,  270,  400 

1900 98, 116,  920 

1902 106,  910,  940 

1908 109,  500,  ooo 

The  increase  in  milk  consumption  has  been  greater  than 
the  increase  in  population,  indicating  that  the  per  capita 
consumption  has  increased.1 

Milk,  unlike  most  foodstuffs,  is  consumed  largely  in  an 
uncooked  state.  Because  of  this  fact,  milk,  when  not  pro- 
duced and  distributed  under  proper  conditions,  may  be- 
come dangerous  as  a  carrier  of  contagious  diseases.  This 

1  "Next  to  bread,  milk  is  more  extensively  used  as  an  article  of  diet  than 
any  other  foodstuff."  —  (J.  H.  Mohler,  A.  M.  V.  M.  D.) 


EXTENT  AND  IMPORTANCE  OF  THIS  INDUSTRY      29 

fact,  in  turn,  is  particularly  important  because  milk  is  an 
important  article  of  diet  of  infants,  children  and  many 
invalids,  all  of  whose  bodies  have  but  slight  power  to  re- 
sist the  inroads  of  disease  germs. 

The  city  of  New  York  in  1908  consumed  438,000,000 
quarts  of  milk,  which  was  produced  in  the  States  of  New 
York,  New  Jersey,  Pennsylvania,  Connecticut,  Vermont, 
Massachusetts,  Ohio  and  Maryland.  Some  of  it  traveled 
350  miles  by  rail  to  reach  the  city.  Over  5000  wagons  were 
employed  in  distributing  it  to  the  consumers. 

The  milk  supply  of  Philadelphia  is  obtained  from  5473 
dairy  farms  located  in  four  states. 

Because  of  the  consumption  of  great  quantities  of  milk 
from  such  widely  scattered  sources,  because  of  the  use  of 
milk  in  the  uncooked  state,  because  of  its  place  in  the  diet 
of  infants  and  invalids,  because  of  the  ease  with  which  it 
may  be  contaminated  with  disease-producing  germs,  and 
because  of  the  fact  that  milk  forms  a  favorable  medium 
for  bacterial  growth,  the  city  milk  supply  is  a  subject  of 
great  importance  to  the  entire  public.  The  problem  of 
how  to  insure  a  sanitary  milk  supply  for  a  large  city  is 
one  of  the  greatest  with  which  food  and  health  officers 
have  to  deal. 

Condition  of  the  City  Milk  Supply  in  Past  Years.  —  The 
realization  of  the  important  role  that  this  subject  plays 
in  the  public  welfare  has  come  only  in  recent  years.  In- 
vestigations into  the  condition  of  the  milk  supply  of  cities 
were  seldom,  if  ever,  made  until  about  two  decades  ago. 
These  first  investigations  showed  conditions  to  be  bad  in 
many  places.  Later  and  more  thorough  investigations 
have  brought  out  some  very  startling  facts. 

Investigations  in  Illinois  Cities.  —  An  investigation  of  the 
milk  supply  of  Chicago  and  other  Illinois  cities  in  1905, 


DAIRY  TECHNOLOGY 


by  J.  M.  Truman,1  revealed  a  very  unsatisfactory  state 
of  affairs.  Some  whole  districts  were  found  supplied  with 
very  good  milk,  but  other  districts,  especially  those  supplied 
chiefly  by  the  small  milk  depots,  received  mainly  poor  milk. 
A  very  great  majority  of  these  small  milk  depots  were 
dirty  and  unsanitary;  many  were  in  dark,  unclean,  ill- 
ventilated  cellars,  where  the  sunlight  never  entered.  And 
in  most  of  these  places  the  milk  was  kept  in  cans,  dipped 
into  open  dishes  when  sold,  and  often  carried  several  blocks 
through  dusty  streets. 

In  the  better  portions  of  the  city,  the  milk  was  delivered 
by  large  dealers  from  wagons,  and  was  of  good  quality, 
except  that  in  some  cases  an  undue  amount  of  sediment 
was  found  in  the  bottles. 

The  following  table  shows  the  results  of  an  examination 
of  several  hundred  samples  of  milk  obtained  in  Illinois 
cities: 


Number 
of 
samples. 

Per  cent  of 
samples  below 
fat  standard. 

Number 
of 
samples. 

Per  cent  of 
samples  showing 
sediment. 

413 
95 
ISO 

95 
325 

32 
20 
50 

9 
19 

89 
232 

143 
212 

68 
66 
68 
88 

Total,  1078 

Average,  27.4 

Total,  676 

Average,  73.5 

Milk  and  Infant  Mortality. — City  health  authorities 
in  the  past  were  more  disposed  to  inspect  milk  for 
preservatives  than  for  cleanliness,  yet  the  latter  is  as 
important  as  the  former.  No  doubt  children  are  occa- 
sionally injured  by  the  indiscreet  use  of  preservatives, 

1  111.  Bulletin  120. 


EXTENT  AND  IMPORTANCE  OF  THIS   INDUSTRY      31 

but  the  number  that  die  from  the  effects  of  milk  which 
has  been  contaminated  with  undesirable  ferments  is 
greater. 

The  death  rate  of  any  city  shows  that  more  children  die 
during  July  and  August  than  at  any  other  time  of  the  year, 
and  that  a  large  percentage  of  these  deaths  are  due  to  in- 
testinal troubles.  In  general,  90  per  cent  of  the  infants 
that  die  are  artificially  fed. 

Balestre  and  Gileta  de  St.  Joseph,  in  France,  showed  that 
from  1892  to  1897  in  every  1000  infant  deaths  under  one 
year  of  age,  385  were  due  to  gastro-intestinal  diseases. 
This  was  the  average  for  the  whole  country.  The  number 
of  deaths  from  this  cause  in  Troyes,  in  1892,  was  700  per 
1000. 

In  42  cities  of  Germany,  in  1906,  the  average  infantile 
death  rate  was  198  per  1000  births.  Of  these,  44  per  cent 
were  due  to  diarrhea. 

The  relation  between  infant  mortality  and  city  milk 
supply  is  becoming  generally  understood  among  medical 
men.  The  high  infantile  death  rate,  especially  during  the 
summer  months,  should  not,  of  course,  be  charged  wholly 
to  a  poor  milk  supply.  Undoubtedly  this  is  simply  one 
factor  which  conspires  with  others  to  cause  the  high  in- 
fantile death  rate. 

In  New  York  City,  it  was  early  recognized  by  the  health 
authorities  that  some  system  of  regulation  of  the  milk 
supply  must  be  established.  The  first  ruling  established 
a  standard  for  the  composition  of  dairy  products.  In 
1902  the  New  York  City  Department  of  Health  made  a 
comprehensive  investigation  of  the  conditions  surround- 
ing the  production,  transportation  and  distribution  of  the 
milk  supply.  The  market  milk  was,  as  a  rule,  from  a 
sanitary  point  of  view,  in  a  bad  condition. 


32  DAIRY  TECHNOLOGY 

Epidemics  Spread  by  Milk.  —  There  are  on  record  over 
500  epidemics  of  typhoid  fever,  scarlet  fever  and  diph- 
theria that  were  traced  to  the  milk  supply. 

One  ,of  the  worst  milk  epidemics  on  record  is  the 
typhoid  epidemic  at  Stamford,  Conn.,  in  1895.  Stamford 
is  a  town  of  15,000  population  and  had  for  some  months 
been  comparatively  free  from  typhoid  fever.  During 
the  nine  days  following  April  14,  1895,  l6°  cases  were 
reported,  and  24  noted  as  suspicious.  147  of  the  160 
cases,  and  all  of  the  suspected  cases,  used  milk  from  one 
dairyman.  Between  April  15  and  May  28,  386  cases 
living  in  1 60  houses  were  reported.  The  dairy  was  closed 
April  21,  and  on  May  6,  just  fifteen  days  after  the  sale 
of  milk  was  stopped,  the  outbreak  had  practically  subsided. 
Of  the  386  cases,  352  (9*^.2  per  cent)  lived  in  houses  taking 
milk  from  the  same  dairyman,  12  were  known  to  have 
used  this  milk  at  a  cafe  supplied  by  him,  2  obtained  it 
at  a  bakeshop  selling  the  same  milk,  and  2  obtained  it 
in  other  ways,  making  368  cases  so  traced,  or  95.3  per  cent. 

Sources  of  Milk  Contamination.  —  Similar  epidemics 
of  scarlet  fever  and  diphtheria  are  on  record,  the  source 
of  the  milk  contamination  being  probably  one  of  the 
following : 

1.  Water  supply. 

2.  Hands  of  milker. 

3.  Can,  pail,  cooler  or  other  utensils. 

4.  Transportation. 

5.  Air  and  dust  of  stable. 

6.  Bottles. 

7.  Deliveryman. 

J.  W.  Eyre  has  shown  by  experiment  that  B.'  typhosus 
and  B.  diphtherias  are  able  to  proliferate  in  milk.  Since 
the  causal  organism  of  scarlet  fever  has  not  been  isolated, 


EXTENT  AND   IMPORTANCE   OF  THIS   INDUSTRY      33 

it  is  not  known  whether  it  may  or  may  not  multiply  in 
milk. 

Bovine  Tuberculosis.  —  Investigations  have  shown  that 
tuberculosis  of  the  bovine  type  is  common  in  children.  The 
infection  may  be  caused  by  the  ingestion  of  meat  from 
tubercular  animals;  it  may  be  caused  by  inhaling  infected 
air;  and  in  all  probability  it  may  be  caused  by  drinking 
milk  from  tuberculous  cows.  Indeed,  when  we  consider 
that  meat  is  usually  cooked  before  being  eaten,  while  milk 
is  used  raw,  and  that  children  consume  a  relatively  small 
amount  of  meat  and  a  very  large  quantity  of  milk,  we 
cannot  but  conclude  that  milk  is  the  main  food  that  dis- 
seminates this  disease  among  children. 

In  milk  examined  for  the  presence  of  tubercle  bacilli, 
an  average  of  5  per  cent  of  all  samples  examined  in  various 
cities  in  this  country  contained  tubercle  organisms  viru- 
lent for  guinea  pigs.  In  many  places  the  percentage  was 
much  higher.  In  Philadelphia,  14.6  per  cent  of  the  samples 
of  milk  examined  were  tuberculous.  Hess  found  16  per 
cent  of  the  milk  supply  of  New  York  City  to  contain  viru- 
lent tubercle  bacilli. 

Butter  and  cheese  are  of  much  less  importance  in  this 
respect,  but  it  has  been  shown  by  Mohler,  Washburn, 
Rogers  and  Doane,  that  tubercle  bacilli  retain  their  viru- 
lence for  six  months  in  butter,  and  for  eight  months  in 
cheese. 

Parke  of  New  York  City  has  found  bovine  tubercle 
bacilli  in  26  per  cent  of  the  cases  of  tuberculosis  in  children 
under  5  years  of  age. 

Of  the  fatal  cases  of  tuberculosis  among  children  inves- 
tigated by  the  German  and  British  tuberculosis  commis- 
sions, about  one-third  was  found  to  be  due  to  the  bovine 
type  of  bacillus. 


34  DAIRY  TECHNOLOGY 

The  lowest  estimate  made  by  the  best  authorities  is  that 
from  2400  to  3200  deaths  are  caused  annually  in  this  coun- 
try, principally  among  children,  by  bovine  tubercle  bacilli. 
Most  authorities  to-day  believe  this  estimate  to  be  too  low. 
Von  Behring  believes  that  tubercular  cows'  milk  fed  to 
infants  is  the  chief  cause  of  tuberculosis  in  man. 


CHAPTER  V. 

IMPROVEMENT  OF  THE  MILK  SUPPLY. 

WHEN  health  authorities  and  the  public  in  general 
came  to  realize  the  close  relationship  between  the  milk 
supply  and  public  health,  many  plans  were  suggested  for 
improving  the  sanitary  conditions  of  the  product. 

The  inspection  and  regulation  of  other  food  products 
were  provided  for  many  years  before  any  attention  was 
given  to  milk. 

Inspection  of  Dairy  Farms  and  of  Milk.  —  Probably 
the  first  legislation  that  pertained  to  the  sale  of  milk  was 
that  enacted  in  the  city  of  Washington  in  1863.  As  early 
as  1873,  the  food  inspectors  of  that  city  recognized  the 
importance  of  the  inspection  of  milk  not  only  in  the  market 
but  at  the  place  of  production.  This  latter  point  was 
not  emphasized  by  sanitarians  until  about  twenty  years 
later.  The  Washington  milk  law  of  1895  was  one  °f  the 
first  to  provide  for  a  proper  inspection  and  regulation  of 
the  milk  supply.  This  law  proposed  to  begin  the  milk 
inspection  at  the  cow  and  to  follow  the  product  as  it 
passed  through  the  hands  of  the  transportation  company, 
the  wholesaler  and  the  retailer,  to  the  ultimate  consumer. 

This  law  made  it  the  duty  of  the  health  officer  of  the 
District  of  Columbia  to  enforce  regulations  to  secure 
proper  water  supply,  drainage,  ventilation,  air  space, 
floor  space,  cleaning  of  all  dairies  and  dairy  farms  within 
the  District,  and  the  isolation  of  diseased  cattle.  No 
milk  could  be  sold  in  the  District  except  that  coming  from 

35 


36  .  DAIRY  TECHNOLOGY 

inspected  farms,  and;  although  the  District  authorities 
could  not  legally  go  beyond  their  territorial  limits  to 
inspect  cows  or  farms,  they  could  refuse  to  admit  milk 
from  farms  not  inspected.  Dairy  farmers  wishing  to 
market  their  product  in  the  District  asked  to  have  the 
agents  of  the  health  authorities  inspect  their  dairies  for 
them. 

Cost  of  Inspection.  Many  cities  now  have  laws  pro- 
viding for  the  inspection  of  dairy  farms  and  of  milk  from 
the  time  it  leaves  the  cow  until  it  reaches  the  consumer. 
The  city  of  Washington  spends  for  this  purpose  $20,000 
annually.  The  Milk  Commissioner  of  Philadelphia  esti- 
mated that  it  would  cost  nearly  $100,000  to  inspect  all 
dairy  farms  that  contributed  the  146,000,000  quarts  of 
milk  consumed  during  the  year  1910.  The  cost  of  this 
inspection  amounts  to  about  0.07  of  a  cent  per  quart. 

Geo.  M.  Whitaker,1  in  calculating  the  extra  cost  of 
producing  clean  milk,  finds  that,  in  order  to  increase  the 
score  of  a  dairy  farm  about  forty-two  points  to  seventy 
points,  in  a  15 -cow  dairy,  an  added  expense  is  incurred  of 
5  cents  per  cow  per  day  for  labor.  When  new  or  additional 
equipments  are  needed,  the  cost  is  still  greater.  Assuming 
that  the  cows  produce  from  4000  to  12,000  pounds  of  milk 
per  year  each,  the  added  expense  for  labor  would  be  about 
one-half  cent  to  one  cent  per  quart.  For  the  extreme  cases 
requiring  new  equipment,  the  expense  would  be  still  greater. 

Fear  that  the  price  of  milk  would  be  advanced  has  kept 
many  a  city  council  from  passing  an  ordinance  requiring 
adequate  milk  inspection,  and  it  has  also  prevented  health 
commissioners  from  enforcing  such  ordinances.  But  such 
an  attitude  is  manifestly  wrong.  Even  though  it  may  cost 
a  little  more  to  produce  clean  milk  than  impure  milk,  the 
1  U,  S,  Dept,  of  Agr,,  Bu,  An,  Ind.  An,  Kept.,  1909. 


IMPROVEMENT  OF  THE  MILK   SUPPLY  37 

increased  cost  is  very  slight,  and,  as  sanitary  milk  is  one  of 
the  cheapest  and  best  foods  we  have,  there  should  be  no 
objection  to  a  slight  increase  in  price,  if  it  be  accompanied 
by  an  improvement  in  the  quality.  The  cause  of  impure 
and  unhygienic  milk  is  not  so  much  a  lack  of  expensive 
equipment,  as  it  is  a  lack  of  clean  methods,  and  the  presence 
of  unhealthy  cows. 

The  Score  Card. — The  inspection  of  dairy  farms  and 
dairies  necessitated  the  adoption  of  a  score  card  to  insure 
uniformity  of  reports  from  various  inspectors.  The  Of- 
ficial Dairy  Instructors'  Association  has  introduced  such 
a  score  card,  that  has  been  adopted  by  the  Dairy  Division 
of  the  United  States  Department  of  Agriculture,  and  is 
being  used  at  the  present  time,  sometimes  in  a  modified 
form,  in  more  than  60  of  the  larger  cities  of  the  country 
and  in  many  smaller  ones.  The  latest  form  of  this  score 
card  is  as  follows: 


38  DAIRY  TECHNOLOGY 

UNITED  STATES  DEPARTMENT  OF  AGRICULTURE, 

BUREAU  OF  ANIMAL  INDUSTRY, 

DAIRY  DIVISION. 


SANITARY  INSPECTION  OF  DAIRIES. 


DAIRY  SCORE   CARD. 

Adopted  by  the  Official  Dairy  Instructors'  Association.     (Subject  to  revi- 
sion at  future  meetings.) 


Owner  or  lessee  of  farm 

P.  O.  address State 

Total  number  of  cows Number  milking 

Gallons  of  milk  produced  daily 

Product  is  retailed  by  producer  in 

Sold  at  wholesale  to 

For  milk  supply  of , 

Permit  No Date  of  inspection 191 

REMARKS.. 


(Signed) 

Inspector. 


IMPROVEMENT  OF  THE   MILK  SUPPLY 


39 


DETAILED   SCORE. 


Equipment. 

Score. 

Methods. 

Score. 

Per- 
fect. 

Allowed. 

Per- 
fect. 

Allowed. 

Cows. 

Health  
Apparently      in      good 
health  i 
If   tested   with    tuber- 
culin once  a  year  and 
no     tuberculosis      is 
found,    or    if    tested 
once   in    six    months 
and  all  reacting  ani- 
mals removed  5 
(If  tested  only  once 
a  year  and  reacting 
animals  found  and  re- 
moved, 2.) 

6 

2 

Cows. 
Cleanliness  of  cows 

8 
6 

6 

2 
2 

3 
8 

9 

Stables. 
Cleanliness  of  stables  
Floor  .                          2 

Walls  i 
Ceilings  and  ledges  .  .  .  i 
Mangers  and  partitions  i 
Windows                        i 

Stable  air  at  milking 
time 

Barnyard  clean  and  well 
drained 

Removal      of      manure 
daily    to    field    or 
proper  pit  
(To  50  feet  from  stable, 
i.) 

Milk  Room. 
Cleanliness  of  milk  room  .  . 

Utensils  and  Milking. 
Care  and  cleanliness  of 
utensils  
Thoroughly      washed 
and  sterilized  in  live 
steam    for    30   min- 
utes    5 
(Thoroughly    washed 
and      placed      over 
steam  jet,  4;  thor- 
oughly washed  and 
scalded  with  boiling 
water,  3;  thoroughly 
washed,  not  scalded, 

2.) 

Inverted  in  pure  air.  .  .3 
Cleanliness  of  milking  
Clean,  dry  hands  3 
Udders     washed     and 
dried  6 
(Udders  cleaned  with 
moist       cloth,       4; 
cleaned     with     dry 
cloth  at  least  15  min- 
utes before  milking, 
i.) 

Bedding  i 
Temperature  of  stable,  i 
Food    (clean  and  whole- 

2 

Water  
Clean  and  fresh  i 
Convenient  and    abun- 
dant    i 

Stables. 
Location  of  stable 

2 
2 



Well  drained  i 
Free  from  contaminat- 
ing surroundings  I 
Construction  of  stable  
Tight,  sound  floor  and 
proper  gutter  2 
Smooth,     tight     walls 
and  ceiling                   i 

4 
4 

Proper   stall,   tie,    and 
manger  .  .                      i 

Light:     Four  sq.   ft.    of 
glass  per  cow 

(Three  sq.  ft.,  3;  2  sq. 
ft.,  2;  i  sq.  ft.,  i;  De- 
duct for  uneven  dis- 
tribution. ) 
Ventilation:      Automatic 
system  
(Adjustable     windows, 
i.) 
Cubic  feet   of  space  for 
cow:  500  to  1000  feet.  .  . 
(Less  than  500  feet,  2 
less  than  400  feet,  i 
less  than  300  feet,  o 
over  1000  feet,  o.) 

3 
3 



DAIRY  TECHNOLOGY 


DETAILED  SCORE.     (Continued) 


Equipment. 

Score. 

Methods. 

Score. 

Per- 
fect. 

Allowed. 

Per- 
fect. 

Allowed. 

Utensils. 
Construction     and      con- 
dition of  utensils  
Water  for  cleaning  
(Clean,  convenient,  and 
abundant.) 
Small-top  milking  pail  
Facilities  for   hot  water 
or  steam  
(Should     be    in     milk 
house,  not  in  kitchen) 
Milk  cooler  
Clean  milking  suits  

Milk  Room. 
Location  of  milk  room  
Free  from  contaminat- 
ing surroundings  i 
Convenient                       I 

i 
i 

3 

i 

i 
i 

2 

2 

Handling  the  Milk. 
Cleanliness  of  attendants  .  . 
Milk  removed  immedi- 
ately from  stable  
Prompt  cooling.  (Cooled 
immediately      after 
milking  each  cow)  .... 
Efficient  cooling;  below 
50°  F. 

i 

2 
2 

5 

(Si°  to  55°,  4J  56°  to 
60°,  2.) 
Storage;  below  50°  F  
(51°  to  55°,  2;  56°  to 
60°,  i.) 
Transportation;   iced    in 
summer  
(For    jacket    or    wet 
blanket  allow  2;  dry 
blanket    or   covered 
wagon,  i.) 

Total 

3 
3 

Construction      of      milk 
room  . 

Floor,  walls,  and  ceil- 
ing    i 
Light,          ventilation, 
screens  i 

Total 

40 

60 

Score  for  equipment plus  Score  for  methods equals FINAL 

SCORE. 

NOTE  i.  —  If  any  filthy  condition  is  found,  particularly  dirty  utensils, 
the  total  score  shall  be  limited  to  49. 

NOTE  2.  —  If  the  water  is  exposed  to  dangerous  contamination  or  there 
is  evidence  of  the  presence  of  a  dangerous  disease  in  animals  or  attendants, 
the  score  shall  be  o. 


IMPROVEMENT  OF  THE   MILK  SUPPLY  41 

Advantages  of  Score  Card  Inspection. — The  score  card 
system  of  inspection  is  found  to  have  the  following  good 
points: 

1.  It  gives  the  health  officer  a  concise,  exact  report,  in 
a  convenient  form,  of  all  dairies  marketing  milk  in  a  given 
district. 

2.  The  score  may  be  used  as  a  basis  for  issuing  licenses. 
Dairies  scoring  below  50  or  60  points  are  in  some  cities 
barred  from  selling  milk  until  the  necessary  improvements 
are  made  to  bring  their  score  up  to  standard. 

3 .  The  health  commissioner  or  person  in  charge  may  use 
the  score  card  as  a  check  on  the  inspectors,  as  these  cards 
indicate  exactly  where  each  inspector  has  been  each  day 
and  how  much  he  has  accomplished. 

4.  One  of  the  greatest  advantages  of  this  method,  if 
properly  used,  is  the  possibility  of  bringing  about  improve- 
ments in  the  dairies  by  means  of  the  publication  of  all 
scores.     When  the  attention  of  the  public  is  called  to  the 
relative  scores  of  the  various  dairymen,  the  man  with  the 
low  score  suffers  a  loss  of  trade,  while  there  is  a  big  demand 
for  the  product  of  the  high-scoring  man.     Publicity  incites 
competition  and  is  a  great  stimulus  to  the  improvement 
of  conditions. 

5.  The  card  tells  the  inspector  exactly  what  to  look 
for,  so  that  it  is  practically  impossible  for  him  to  overlook 
any  important  point. 

6.  This  system  is  generally  well  received  by  the  dairy- 
men, because  it  is  thorough,  easily  understood,  and  abso- 
lutely fair. 

7.  It  enables  inexperienced  inspectors  to  do  efficient 
work,  because  of  the  detailed  explanations  on  the  card. 

8.  It  educates  the  producer,  points  out  his  failings,  and 
instructs  him  how  to  improve  his  conditions. 


DAIRY  TECHNOLOGY 


9.  It  develops  better  business  methods  on  the  farm,  and 
usually  leads  to  greater  profits. 

10.  The  milk  dealer  is  enabled  to  discriminate  between 
producers,  to  locate  the  better  dairies,  and  thus  to  secure 
a  higher  grade  of  milk. 

Results  of  Score-card  Inspections.  A  report  of  the 
Richmond,  Va.,  board  of  health,  October,  1907,  shows 
the  improvement  in  dairies  during  six  months  following  the 
adoption  of  the  score-card  system. 


First  score. 

Last  score. 

Points  gained. 

Percentage 
gained. 

Average  

33-4 

56.8 

23-4 

76.8 

The  following  extract  from  the  Thirteenth  Report  of  the 
Board  of  Health  of  Montclair,  N.  J.,  shows  a  marked  im- 
provement in  dairy  conditions  due  to  the  use  of  the  score 
card: 


Scores. 

1906. 

1907. 

Number  of 
dairies. 

Percentage  of 
total. 

Number  of 
dairies. 

Percentage  of 
total. 

Below  50  
Between  70  and  100  .  .  .  . 

6 
35 

I3-05 
76.09 

O 
45 

O 
90 

Many  large  dealers  either  require  in  their  contracts  with 
the  producer  that  his  score  be  up  to  a  certain  standard,  or 
they  pay  a  reduced  price  for  milk  from  low-scoring  dairies 
and  a  premium  for  milk  from  high-scoring  dairies. 

This  is  true  in  Geneva,  N.  Y.,  where  the  city  authorities 
have  carried  on  a  publicity  campaign,  and  have  used  their 
influence  to  induce  the  milk  dealers  to  buy  from  the  pro- 


IMPROVEMENT  OF  THE  MILK  SUPPLY 


43 


ducer  on  the  basis  of  the  score  placed  upon  the  dairy  by  the 
city  inspector.  At  the  beginning  of  this  campaign,  condi- 
tions were  about  the  same  as  are  found  in  many  small 
cities,  and  the  improvement  from  time  to  time  may  be 
noted  in  the  following  table: 


Percentage  of  dairies. 

Excellent. 

Good. 

Medium. 

Poor. 

Beginning  

0 

2-9 
8.6 

12.8 
12.8 

5-o 
58.9 
82.8 

74-4 
87.2 

57-5 
38.2 
8.6 

12.8 

o 

37-5 
O 
O 

o 
o 

End  of  first  year  

End  of  second  year  
End  of  third  year 

ist  quarter  of  fourth  year.  .  .  . 

Inspection  of  City  Milk  Plants. — In  the  larger  cities  there 
is,  in  most  instances,  a  middle  man  between  the  producer 
and  the  consumer.  At  the  place  of  business  of  this  middle 
man,  the  milk  may  simply  be  cooled  and  loaded  into  wagons 
for  distribution,  or  it  may  be  clarified,  pasteurized  and 
standardized;  it  may  be  a  small  place  with  but  little  equip- 
ment or  it  may  be  a  huge  building  containing  much  ex- 
pensive apparatus.  In  either  case,  there  is  necessity  for 
supervision  by  the  board  of  health,  and  the  following 
score  card  has  been  devised  for  this  purpose  by  the  Dairy 
Division  of  the  United  States  Department  of  Agriculture: 


44 


DAIKV  TECHNOLOGY 


SANITARY   INSPECTION   OF  CITY  MILK   PLANTS. 


Boor* 

Score. 

Equipment. 

Per- 
toot, 

Allowed. 

Methods. 

IV, 

feet. 

Allowed. 

Plant: 
Location  

IS 

Plant: 
i  'K-anliness  

15 

Convenience,         i- 

Floor  6 

\\alls                       ..    4 

Arrangements 

7 

Ceilings  

Doors      

Convenience  .          \ 

Constructions  
Floor  ...            ,  .  s 

0 

Windows  
Good  order  
Free  from  odors 

Walls    . 

NLu'hinerv  aiul  utensils: 

Ceilinn                   i 

^  'U'anliness 

as 

Light 

I 

Milk: 

Ventilation 

i 

Handling 

25 

Screens  .  .  . 

l 

(Claritx  in^,  pas 

Machinery  ami  uten- 
sils . 

teurizing,  cool- 
ing, bottling^  . 

Kindamlqualits  ,  7 
(.Steam    or   hot 
water        bottle 

Stonun 

45°  F.  or  below.  .  .20 
45°  F-  to  50"  F.  .      15 
50°  to  55°  F.  ..        10 

30 

er,           bottling 

machine,    dry- 
ing            raeks. 
e  rates.       sinks, 

pMteurtwr, 

coM  storage.) 
Condition    .             7 

Arrangement  6 
Water  tor  cleaning 

JS 

\V  u'ons 

6 

Construction,     eon 
ilition 

4 

Cleanliness  3 
Protection  of  prod- 

1  1 

net  ...                        ; 

l.ivation                  4 

Salesroom: 

Cleanliness 

A 

Equipment  3 

1OO 

IOO 

Additfowl  Deductions. 

For   exceptionally    bail 
conditions: 

Additional  Deductions. 
For  exceptionally  bad 
conditions: 

, 

Total  deductions 

Total  deductions 

Net  total 

Net  total 

Score  for  nu'tluxls — ; 

Score  for  equipment .  . . —    — ; 
Total,  to  be  divided  by  3. 
Final  Score. , 


multiplied  by  2 
multiplied  by  i 


IMPROVEMENT  OF  THE  MILK  SUPPLY 


45 


Milk  and  Cream  Contests.— Another  method  of  arous- 
ing competition  and  inciting  dealers  to  deliver  the  best 
quality,  is  the  holding  of  milk  and  cream  contests.  These 
contests  are  usually  given  great  publicity.  Hence  they 
form  excellent  advertisements  for  the  dairymen  participat- 
ing, and  particularly  profitable  advertisements  for  those 
who  make  a  good  showing  in  the  contest. 

The  first  milk  and  cream  contest  in  this  country  was  held 
at  the  National  Dairy  Show  in  1906,  under  the  supervision 
of  the  Dairy  Division  of  the  United  States  Department  of 
Agriculture.  The  object  of  the  contest  was,  first,  educa- 
tional; second,  to  determine  the  possibilities  of  long-dis- 
tance shipments  and  long  holdings  of  milk  produced  under 
sanitary  conditions  and  kept  cold;  third,  to  test  the  ef- 
ficiency and  practicability  of  a  score  card  for  this  class  of 
dairy  products.  Milk  was  sent  to  this  contest  from  thir- 
teen different  states,  and  it  was  here  demonstrated  that 
clean  milk,  held  at  a  low  temperature,  can  be  shipped  a 
thousand  miles  and  be  kept  sweet  for  a  period  of  over  five 
weeks. 

Since  that  time,  states  and  cities  have  employed  the  milk 
and  cream  contest  with  very  gratifying  results. 

The  score  card  used  is  as  follows: 


SCORE  CARD  FOR  MARKET  MILK. 


Exhibitor. 


Address. 


NUMERAL  SCORE. 


Flavor, 
40. 

Composition, 
25. 

Bacteria, 

20. 

Acidity, 
5. 

Appearance  of 
package  and 
contents,  lo. 

Perfect  score, 
loo. 

Judge's  score. 

DAIRY  TECHNOLOGY 


DESCRIPTIVE  SCORE. 


Flavor. 

Composition. 

Bacteria. 

Acidity. 

Package  and 
contents. 

Excellent  

Perfect. 

1  Fat,  —  per 
j     cent. 

Perfect. 
j   Total  
Liquefiers. 

Perfect. 

(   -  per    ] 
{     cent,    j 

Perfect. 
Foreign  matter. 
Metal  parts. 
Unattractive. 

Good  .                      .   . 

Fair.  .  . 

Bad  
Flat.. 

Bitter.  .  . 
Weedy 

)  Solids,  not 
Jfat,  —  per 
)     cent. 

Garlic  
Silage 

1  

Smothered  
Other  taints  

Remarks  .         

t  Judge. 

Date.  .  . 

DIRECTIONS  FOR  SCORING 

Flavor. 

If  rich,  sweet,  clean,  and  pleasant  flavor  and  odor,  score  perfect  (40). 
Deduct  for  objectionable  flavors  and  odors  according  to  conditions  found. 

If  3.25  per  cent  fat  or  above  and  8.5  per  cent  solids  not  fat  or  above, 
score  perfect  (25).  Deduct  i  point  for  each  one-fourth  per  cent  fat  below 
3.25  and  i  point  for  each  one-fourth  per  cent  solids  not  fat  below  8.5. 

Bacteria. 

Less  than  10,000  per  cubic  centimeter (perfect) 20 

Over  10,000  and  less  than  25,000  per  cubic  centimeter 19 

Over  25,000  and  less  than  50,000  per  cubic  centimeter 18 

Over  50,000  and  less  than  75,000  per  cubic  centimeter 17 

Over  75,000  and  less  than  100,000  per  cubic  centimeter 16 

Deduct  i  point  for  each  25,000  above  100,000 

When  an  unusually  large  number  of  liquefying  bacteria  are  present, 
further  deduction  should  be  made  according  to  conditions  found. 

Acidity. 

If  0.2  per  cent  or  below,  score  perfect  (5).  Deduct  i  point  for  each  o.oi 
per  cent  above  0.2  per  cent.  (If  Mann's  test  is  used,  discontinue  adding 
indicator  on  first  appearance  of  a  pink  color.) 

Appearance  of  Package  and  Contents. 

If  a  package  is  clean,  free  from  metal  parts,  and  no  foreign  matter  can 
be  detected  in  the  contents,  score  perfect  (10).  Make  deductions  accord- 
ing to  conditions  found. 


IMPROVEMENT  OF  THE   MILK  SUPPLY  47 

Such  contests  greatly  improve  the  milk  supply  if  the 
consumer  is  interested  in  the  project  and  is  willing  to  pay 
a  slightly  higher  price  for  milk  of  good  quality  than  for 
that  of  poor  quality. 

Number  of  Inspections  Made  in  New  York  City.  —  Dur- 
ing the  year  1908,  there  were  inspected  and  rated  on  a  score 
card,  41,937  dairy  farms  that  sell  milk  in  New  York  City. 
Inspectors  within  the  city  examined  101,049  specimens 
of  milk,  and  took  6268  samples  for  chemical  analysis, 
and  about  the  same  number  for  bacteriological  examina- 
tion. 26,500  quarts  of  milk  were  destroyed  for  being 
above  50°  F.,  and  the  total  milk  destroyed  by  inspectors 
for  all  reasons  was  43,140  quarts. 

Limitations  of  General  Inspection.  —  Whenever  a  sys- 
tem of  inspection  is  properly  carried  out,  many  improve- 
ments may  be  noted  in  the  sanitary  condition  of  farms, 
dairies,  and  depots.  However,  in  spite  of  the  continuous 
and  thorough  inspection  in  New  York  City,  16  per  cent 
of  the  samples  analyzed  were  found  to  be  below  standard, 
and  25  per  cent  of  the  samples  examined  bacteriologically 
contained  over  1,000,000  bacteria  per  cubic  centimeter. 
The  dairy  farms  inspected  and  scored  in  New  York  City 
in  1908  showed  the  following  condition: 

2,179  dairies  scored  between  76  and  100. 
24,130  dairies  scored  between  51  and  75. 
15,628  dairies  scored  below  50. 
Average  score  —  57. 

A  similar  inspection  and  scoring,  in  New  York  City,  of 
creameries,  or  places  where  milk  is  handled,  revealed  a 
somewhat  better  condition. 

613  creameries  scored  between  76  and  100. 
671  creameries  scored  between~5i  and  75. 
162  creameries  scored  below  50. 
Average  score  —  71. 


48  DAIRY  TECHNOLOGY 

It  is  evident  from  these  figures  that  there  is  still  room 
for  improvement.  However,  although  the  object  of  city 
milk  inspection  is  to  improve  the  general  sanitary  con- 
dition of  the  milk  supply,  this  general  inspection  does  not 
aim,  nor  is  it  in  itself  sufficiently  thorough,  to  insure  a 
product  absolutely  pure  and  sanitary  and  safe  for  invalid 
or  infant  feeding.  The  good  will  and  cooperation  between 
health  officers  and  dairymen  for  the  mutual  good  of  all  is 
essential. 

-  Classes  of  Milk.  —  The  general  milk  supply  of  many 
cities  is  divided  into  classes  according  to  certain  standards, 
such  as  the  degree  of  sanitation  observed  in  the  production 
and  handling  of  the  milk,  the  treatment  of  milk  before 
delivering  (pasteurization),  or  the  amount  of  supervision 
by  health  authorities. 

All  milk  in  New  York  City  must  be  sold  under  the  follow- 
ing grades  or  designations  in  accordance  with  the  regula- 
tions adopted  by  the  Board  of  Health: 

/  Milk.  —  This  term  shall  be  applied  to  cows'  milk  which 
conforms  to  the  requirements  of  the  Sanitary  Code  and 
which  does  not  meet  the  requirements  of  milk  sold  under 
other  grades  or  designations  herein  provided  for. 

Selected  Milk.  —  The  minimum  requirements  are  as 
follows: 

1.  Only  such  cows  shall  be  admitted  to  the  herd  as 
are  free  from  all  diseases  of  the  udder,  and  from  clinically 
manifest  tuberculosis. 

2.  That  all  the  cows  be  examined  clinically  each  year 
by  a  veterinarian  of  the  Department  of  Health;   all  cows 
with  any  disease  of  the  udder,  or  with  clinically  manifest 
tuberculosis,  to  be  excluded  from  the  herd  and  farm.     It 
shall  be  unlawful  to  sell  or  use  the  milk  from  such  cows 
for  food  purposes. 

3.  That  the  milk  shall  never  contain  more  than  60,000 


IMPROVEMENT   OF   THE   MILK   SUPPLY  49 

germs   per   cubic  centimeter   in  winter,   nor   more   than 
100,000  germs  per  cubic  centimeter  in  summer. 

4.  That  such  milk  be  delivered  to  the  consumer  only 
in  sealed  bottles,  which  shall  have  been  filled  at  the  dairy 
or  creamery,  and  shall  be  labeled  with  the  date  of  the  earli- 
est milking  whose  milk  forms  part  of  the  contents  of  the 
bottle. 

5.  That  such  milk  be  delivered  to  the  consumer  within 
thirty-six  hours  after  milking. 

Inspected  Milk.  — -  Which  milk  produced  under  the 
supervision  of  a  Milk  Commission  appointed  by  the  Med- 
ical Society  of  the  County  of  New  York  or  by  the  Medical 
Society  of  the  County  of  Kings,  or  under  certificates 
for  "  Inspected  Milk,"  issued  by  said  Commission.  No 
milk,  however,  shall  be  held,  kept,  offered  for  sale  or  sold 
and  delivered  as  inspected  milk  in  the  City  of  New  York 
which  is  produced  under  requirements  less  than  those  of 
the  said  Board  of  Selected  Milk. 

Guaranteed  Milk.  —  The  minimum  requirements  are  as 
follows : 

1.  That  only  such  cows  be  admitted  to  the  herd  as  have 
not  re-acted  to  a  diagnostic  injection  of  tuberculin. 

2.  That  all  such  cows  be  tested  annually  with  tuberculin, 
and  all  re-acting  animals  be  excluded  from  the  herd. 

3.  That  the  milk  shall  not  contain  more  than  30,000 
germs  per  cubic  centimeter  when  delivered  to  the  consumer. 

4.  That  the  milk  be  delivered  to  the  consumer  only  in 
sealed  bottles  which  shall  have  been  filled  at  the  dairy, 
and  shall  bear  a  label  giving  the  name  of  the  dairy,  and  the 
date  of  the  earliest  milking  at  which  the  milk  forming  part 
of  the  contents  was  drawn. 

5.  That  such  milk  be  delivered  to  the  consumer  within 
thirty-six  hours. 

Certified  Milk.  —  Which  is  milk  certified  by  the  Milk 
Commission  appointed  by  the  Medical  Society  of  the 
County  of  New  York  or  the  Medical  Society  of  the  County 
of  Kings  as  being  produced  under  the  supervision  and  in 
conformity  with  the  requirements  of  that  Commission 


50  DAIRY  TECHNOLOGY 

as  laid  down  for  Certified  Milk.  No  milk,  however,  shall 
be  held,  kept,  offered  for  sale  or  sold  and  delivered  as 
Certified  Milk  in  the  City  of  New  York  which  is  produced 
under  requirements  less  than  those  of  the  said  Board  for 
Guaranteed  Milk. 
Pasteurized  Milk: - 

1.  Pasteurization  of  milk  must  be  carried  out  under  a 
permit  therefor  issued  by  the  Board  of  Health,  in  addition 
to  the  usual  permit  for  milk  required  by  Section  56  of  the 
Sanitary  Code. 

2.  The  milk  after  pasteurization  must  be  at  once  cooled 
and  placed  in   sterilized   containers,   and   the  containers 
sealed. 

3.  All  containers  in  which  pasteurized  milk  is  delivered 
to  the  consumer  shall  be  plainly  labeled  "  pasteurized." 
The  labels  must  also  bear  the  date  and  hour  when  the 
pasteurization   was   completed,    the   degree   of   the   heat, 
and  the  length  of  time  exposed  to  the  heat,  and  the  name 
of  the  dealer. 

4.  Pasteurized  milk  must  be  delivered  to  the  consumer 
within  twenty-four  hours  of  the  pasteurization. 

5.  No  milk  shall  be  pasteurized  a  second  time. 

6.  No   milk   which   contains   an   excessive   number   of 
bacteria  shall  be  pasteurized. 

The  classification  of  market  milk  into  the  following 
three  grades  is  suggested  by  the  Bureau  of  Animal  Indus- 
try, United  States  Department  of  Agriculture.  A  fourth 
grade  is  added  by  the  authors. 

1.  Certified  Milk. 

2.  Inspected  Milk. 

3.  Pasteurized  Milk. 

4.  Modified  Milk. 

The  use  of  these  terms  is  recommended  to  be  limited 
to  the  following: 

Certified  milk  is  the  product  of  dairies  that  are  subject 
to  periodic  inspection  by  a  medical  milk  commission, 


IMPROVEMENT  OF  THE  MILK  SUPPLY  51 

the  products  of  such  dairies  being  subject  to  frequent 
chemical  and  bacteriological  examination.  The  cows, 
barns,  milk  house,  utensils  and  milkers  must  come  up  to 
a  very  high  standard  of  sanitation.  The  manner  of  hand- 
ling the  milk,  its  chemical  composition  and  bacterial  con- 
tent are  carefully  prescribed.  It  is  certified,  by  an  author- 
ized officer,  to  be  absolutely  pure  and  sanitary. 

Inspected  milk  is  produced  and  handled  under  condi- 
tions similar  to  those  under  which  certified  milk  is  pro- 
duced and  handled,  but  to  not  quite  so  high  a  degree  of 
perfection,  and  the  product  is  not  certified  to  by  a  milk 
commission,  or  an  authorized  health  officer. 

Pasteurized  milk,  though  clean  and  fresh,  is  of  less 
known  origin,  and  is  subjected  to  heating  to  a  temperature 
of  150°  F.  for  20  minutes,  or  160°  F.  for  10  minutes,  and 
immediately  cooled  to  a  temperature  not  exceeding  50°  F. 

Modified  milk  is  sanitary  milk,  the  composition  of 
which  is  modified  to  conform  with  the  food  requirements 
of  persons  unable  «to  use  milk  in  its  natural  state.  Such 
modification  should  be  done  under  supervision  of,  or  by 
prescription  of,  a  physician  or  milk  expert. 

Results  of  the  Improvement  of  Milk  Supply.  —  The 
chief  purpose  of  our  present-day  extensive  milk  inspection 
and  the  establishment  of  various  grades  of  milk  is  to  supply 
a  sanitary  cheap  food  and  to  save  lives.  The  success 
of  such  inspections  must  then  be  measured  by  their  effi- 
ciency in  accomplishing  these  ends. 

The  milk-inspection  service  has  lessened  the  danger  of 
severe  epidemics  of  contagious  diseases  due  to  milk  in- 
fection. The  most  important  and  extensive  service  ex- 
pected of  milk  inspection  is  to  diminish  the  mortality 
from  diarrheal  diseases  of  children  under  two  years  of 
age.  In  Washington,  D.  C.,  the  death  rate  from  diarrhea 


52  DAIRY  TECHNOLOGY 

and  enteritis  among  infants  during  the  fiscal  year  following 
the  enactment  of  the  milk-inspection  law  in  1895,  was 
1 68  per  100,000  of  population.  The  next  year  it  fell  to  151 ; 
the  third  year  to  136;  and  the  fourth  year  to  no.  In 
1903  it  was  91;  in  1905,  104;  in  1906,  97. 

Infants'  Milk  Depots  in  New  York.  —  The  improve- 
ment of  milk  supply  by  pasteurization  is  demonstrated 
by  the  reports  of  the  Nathan  Straus  depots  and  the  orphan 
asylum  on  Randall's  Island,  New  York  City. 

In  1893,  Nathan  Straus  established  a  depot  for  the  dis- 
pensing of  pasteurized  milk  for  infant  feeding.  In  this 
year  34,400  bottles  of  milk  were  dispensed;  in  1906,  17 
Straus  stations  dispensed  3,142,253  bottles  and  1,078,405 
glasses  of  pasteurized  milk. 

Just  prior  to  the  beginning  of  this  work  by  Straus,  the 
death  rate  of  children  under  5  years  of  age  in  New  York 
City  was  96.2  out  of  every  1000.  In  1906  the  death  rate 
had  fallen  to  55  per  1000,  due,  in  a  large  measure,  to  the 
improvement  of  the  milk  supply  by  pasteurization. 

At  the  rate  of  mortality  of  1892,  there  would  have  been 
27,169  deaths  of  children  under  5  years  of  age  in  1906, 
instead  of  the  15,534  that  actually  occurred.  A  general 
milk  inspection  was  in  operation  at  this  time,  and  no  doubt 
had  some  part  in  reducing  the  death  rate.  There  were 
other  agencies  at  work  which  contributed  toward  accom- 
plishing the  same  results,  such  as  the  campaign  of  fresh 
air  for  children,  use  of  diphtheria  antitoxin,  improved  tene- 
ment houses,  etc. 

The  efficiency  of  pasteurization  under  commercial  con- 
ditions is  indicated  in  the  following  data  collected  in  Chi- 
cago in  1909.  A  bacterial  examination  of  829  samples 
of  milk  during  seven  weeks  ending  September,  1909, 
showed  that  the  unpasteurized  milk  contained  5,547,502 


IMPROVEMENT  OF  THE  MILK  SUPPLY  53 

bacteria  per  cubic  centimeter  and  the  pasteurized  944,465. 
It  is  probable  that  practically  all  bacteria  in  the  vege- 
tative condition  (this  includes  all  pathogenic  organisms) 
were  destroyed. 

At  the  present  time  the  Bureau  of  Municipal  Research 
has  charge  of  the  pure-milk  crusade,  and  the  lowering  of 
the  infant  death  rate  in  New  York  City.  During  some 
of  the  hot  weeks  of  the  summer  of  1911  the  Bureau  had 
about  5000  babies  under  its  direct  care. 

Seventy-five  milk  depots  form  the  centers  from  which 
this  extensive  work  is  carried  on.  At  the  depots  are  250 
trained  nurses  who  distribute  sanitary  milk,  prescribe  for 
babies  and  advise  and  teach  mothers  how  to  feed  and 
care  for  their  children.  Physicians  are  in  attendance  at 
the  depots  at  certain  hours  during  the  day  to  attend  to 
the  more  serious  cases.  146  visiting  nurses  go  to  the 
houses  where  there  are  young  children,  and  teach  the 
mothers  home  sanitation,  and  influence  them  to  procure 
from  the  depot  whatever  milk  may  be  necessary  for  the 
children. 

It  is  here  demonstrated  that  the  distribution  of  clean 
milk  combined  with  the  education  of  mothers  is  one  of 
the  most  economical  and  efficient  methods  of  reducing 
infant  mortality. 

Milk  Depots  in  Other  Cities.  —  The  first  definite  im- 
provements in  any  milk  supply  were  made  by  a  few  insti- 
tutions that  prepared  and  dispensed  a  sanitary  product 
for  infant  feeding.  Probably  the  first  of  these  institu- 
tions in  this  country  was  the  Eastern  Dispensary  of  New 
York  City,  which,  in  1889,  dispensed  sanitary  milk  for 
infant  feeding. 

Since  that  time,  about  three  hundred  infants'  milk 
depots,  as  they  have  come  to  be  known,  have  been  opened 


54  DAIRY  TECHNOLOGY 

in  some  thirty  cities  in  this  country.  Many  of  these  are 
supported  by  private  philanthropy,  others  by  a  city  board 
of  health  or  board  of  charities.  In  all  cases  they  are 
under  the  supervision  of  persons  qualified  to  attend  to 
the  bacterial,  chemical  and  sanitary  condition  of  the 
milk.  The  milk  of  various  depots  is  certified,  pasteurized 
or  modified,  and  in  several  cases  two  of  these  classes  of 
milk  are  supplied  from  the  same  depot.  The  milk  is 
commonly  put  up  in  bottles  containing  but  one  feeding, 
which  bottles  are  so  designed  that  they  cannot  stand  on 
end  and,  therefore,  cannot  be  left  standing  open.  Milk 
of  widely  different  formulas  is  put  up  at  these  depots; 
the  following  is  taken  as  an  example: 

Milk ounces,  64 

Limewater „  4 

Milk  sugar „  6 

Filtered  water ((  60 

The  infants,  in  the  care  of  New  York  City  authorities 
were  fed  on  milk  from  carefully  selected  herds.  The 
death  rate  among  these  infants,  for  the  years  1895  to  ^97 
inclusive,  was  41.8  per  cent.  Early  in  1898,  a  pasteurizing 
plant  was  installed.  No  other  change  in  hygiene  or  diet 
was  made,  but  the  death  rate  dropped  to  19.8  in  1898 
and  averaged  21.75  for  the  succeeding  six  years. 

Investigations  of  the  cause  of  the  high  death  rate  among 
infants  and  young  children  have  revealed,  in  numerous 
instances,  that  the  number  of  deaths  among  children 
bears  a  direct  relation  to  the  quality  of  the  milk  consumed. 
Money  spent  to  improve  the  milk  supply  buys  and  saves 
the  lives  of  many  infants.  It  is  cheaper  for  even  the 
poorest  people  to  pay  a  higher  price  for  a  high-grade  milk 
than  to  buy  an  unsanitary  product  for  a  cent  or  two  less 
per  quart. 


CHAPTER    VI. 

CERTIFIED  MILK. 

INVESTIGATIONS  show  that  market  milk  is  improved  by 
general  inspection,  and  that,  by  grading  or  classifying, 
some  milk  of  very  high  quality  can  be  brought  upon  the 
market.  For  a  general  supply  of  milk  to  be  used  by  healthy 
adults  or  in  cooking,  the  problem  is  not  so  great,  because 
probably  no  great  harm  will  come  from  the  use  of 


FIG.  i.  —  Interior  view  of  South  Dakota  State  College  dairy  barn,  showing 
clean  cows  in  a  clean,  well-ventilated  and  comfortable  place. 

ordinary  market  milk  produced  in  compliance  with  our 
present  laws  and  regulations.  But  for  invalid  or  infant 
feeding,  a  much  better  quality  is  necessary. 

Origin  of  the  Term  "Certified  Milk."  — This  term, 
so  far  as  known,  was  coined  by  Dr.  Henry  L.  Coit  of 
Newark,  N.  J.,  who  was  perhaps  the  foremost  man  in  the 

55 


56  DAIRY  TECHNOLOGY 

originating  and  establishing  of  the  first  milk  commission. 
The  term  was  registered  in  the  United  States  Patent 
Office  to  protect  it  from  being  degraded  by  dairymen  not 
producing  milk  under  supervision  of  a  medical  commission. 
Some  states  have  passed  laws  limiting  the  use  of  this  term 
to  milk  of  sufficiently  high  quality  to  come  up  to  Dr.  Coit's 
standard  for  certified  milk. 

Certified  milk  is  sanitary  milk  produced  under  the 
strict  supervision  and  according  to  rules  of  some  health 
authorities.  The  herd  producing  the  milk  is  examined  as 
to  its  healthfulness  at  intervals.  The  sanitary  condition 
of  barn  and  all  surroundings,  bacterial  content  and  age 
of  milk  are  carefully  watched.  If  these  conditions  come 
up  to  the  standard  the  owner  of  the  place  receives  a  cer- 
tificate showing  that  he  is  authorized  to  sell  his  milk  as 
certified  milk. 

Certified  milk  has  all  the  qualifications  of  a  perfectly 
sanitary  and  hygienic  food  but  the  price  is  so  high  as  to 
be  almost  prohibitory  for  the  mass  of  common  people. 
The  only  alternative  seems  to  be  pasteurized  milk.  This 
can  be  supplied  at  a  reasonable  cost  and,  if  properly  pasteur- 
ized, will  be  practically  as  sanitary  and  hygienic  as  certified 
milk.  However,  it  is  very  necessary  that  the  pasteuriza- 
tion be  properly  done,  and  to  insure  this  all  pasteurizing 
plants  should  be  carefully  and  frequently  inspected  by 
competent  authorities. 

The  quantity  of  certified  milk  produced  in  this  country 
is  less  than  one  per  cent  of  the  total  amount  of  market 
milk  annually  consumed.  Nevertheless,  this  product  is 
of  very  great  value  in  feeding  infants  and  invalids;  it 
has  aided  in  reducing  the  death  rate  among  children  and 
has  had  an  indirect  beneficial  influence  upon  the  general 
milk  supply. 


CERTIFIED   MILK  57 

The  First  Medical  Milk  Commission.  —  In  the  year  1890 
the  Medical  Society  of  New  Jersey  started  a  movement  to 
effect  an  improvement  in  the  milk  supply,  which  resulted 
in  the  formation  of  "  The  Medical  Milk  Commission  of 
Essex  County,  New  Jersey."  Since  that  time  many  others 
have  been  formed  in  various  cities  upon  a  similar  plan. 

Milk  Commissions.  —  A  milk  commission  usually  con- 
sists of  from  5  to  12  men,  as  a  rule  physicians,  but  some- 
times including  business  men  who  are  interested  in  the 
welfare  of  the  city.  This  board  serves  without  pay;  but 
the  chemist,  bacteriologist  and  veterinarian,  who  do  the 
inspecting,  commonly  receive  a  fee.  The  first  commission 
and  several  of  the  later  ones  formed  contracts  with  the 
producers,  wherein  were  exact  specifications  for  all  the 
details  of  the  dairy  and  its  management.  However,  most 
of  the  present-day  commissions  simply  fix  the  required 
standard  and  leave  the  details  of  the  work  to  the  dairy- 
men's judgment.  The  conditions  surrounding  the  pro- 
duction and  handling  of  the  milk  are  necessarily  about  as 
good  as  the  commission  could  demand,  or  it  would  not  be 
possible  to  keep  the  milk  up  to  the  high  standard  required. 

Requirements  of  the  Milk  Commission  of  New  York 
City.  —  In  New  York  City  no  contract  is  made  with  the 
dairymen,  but  a  circular  is  sent  them  giving  information 
concerning  the  production,  standards  and  general  re- 
quirements of  certified  milk.  This  circular  reads  as 
follows: 

The  commission  has  fixed  upon  a  maximum  of  30,000 
germs  of  all  kinds  per  cubic  centimeter  of  milk,  which 
must  not  be  exceeded  to  obtain  the  endorsement  of  the 
commission.  This  standard  must  be  attained  solely  by 
measures  directed  toward  scrupulous  cleanliness,  proper 
cooling,  and  prompt  delivery. 


58  DAIRY  TECHNOLOGY 

The  milk  certified  by  the  commission  must  contain  not 
less  than  4  per  cent  of  butter  fat  on  the  average,  and  have 
all  other  characteristics  of  pure,  wholesome  milk. 

Milk  must  not  be  sold  as  certified  more  than  twenty-four 
hours  after  its  arrival  in  New  York  City. 

Dealers.  In  order  that  dealers,  who  incur  the  expense 
and  take  the  precautions  necessary  to  furnish  a  truly  clean 
and  wholesome  milk,  may  have  some  suitable  means  of 
bringing  these  facts  before  the  public,  the  commission 
offers  them  the  right  to  use  caps  on  their  milk  jars  stamped 
with  the  words:  "  Certified  by  the  Milk  Commission  of  the 
Medical  Society  of  the  County  of  New  York."  The  dealers 
are  given  the  right  to  use  these  certificates  when  their 
milk  is  obtained  under  the  conditions  required  by  the 
commission  and  conforms  to  its  standards. 

In  accordance  with  a  law  passed  at  the  last  legislature, 
the  word,  "  Certified,"  may  be  used  on  the  cap  only  when 
accompanied  by  the  name  of  the  society  which  certifies  it. 

The  tinned  sealed  cap,  authorized  by  the  commission, 
must  be  used  on  all  the  certified  milk  passing  through  the 
hands  of  dealers  selling  milk  other  than  the  certified.  These 
caps  are  sent  by  the  makers,  only  to  the  farm  where  the 
milk  is  bottled. 

The  name  of  the  farm  from  which  the  milk  comes  must 
appear  on  either  the  paper  cap  or  the  tin  cap. 

Each  bottle  of  milk  must  be  dated  on  the  date  of  bot- 
tling. 

The  milk  commission  looks  to  the  dealers  for  its  fee. 

The  dealer  is  expected  to  send  a  bottle  of  milk  each  week 
to  the  research  laboratory  of  the  department  of  health, 
taken  at  random  from  the  day's  supply  for  examination, 
by  experts  for  the  commission. 

The  dealers  are  to  furnish  deep,  covered  boxes  for  the 
certified  milk. 

The  required  conditions  at  the  farm  are  as  follows: 

i.  The  Barnyard. — The  barnyard  should  be  free  from 
manure  and  well  drained,  so  that  it  may  not  harbor  stag- 
nant water.  The  manure  which  collects  each  day  should 
not  be  piled  close  to  the  barn,  but  should  be  taken  several 


CERTIFIED  MILK  59 

hundred  feet  away.  If  these  rules  are  observed  not  only 
will  the  barnyard  be  free  from  objectionable  smell,  which 
is  an  injury  to  the  milk,  but  the  number  of  flies  in  the 
summer  will  be  considerably  diminished.  These  flies  are 
an  element  of  danger,  for  they  are  fond  of  both  filth  and 
milk  and  are  liable  to  get  into  the  milk  after  having  soiled 
their  bodies  and  legs  in  recently  visited  filth,  thus  carrying 
it  into  the  milk. 

2.  The  Stable. — In  the  stable  the  principles  of  cleanliness 
must  be  strictly  observed.     The  room  in  which  the  cows 
are  milked  should  have  no  storage  loft  above  it;    where 
this  is  not  feasible  the  floor  of  the  loft  should  be  tight,  to 
prevent  the  sifting  of  dust  into  the  stable  beneath. 

The  stables  should  be  well  ventilated,  lighted,  and 
drained,  and  should  have  tight  floors,  preferably  of  cement, 
never  of  dirt. 

They  should  be  whitewashed  inside  at  least  twice  a  year, 
unless  the  walls  are  painted  or  of  smooth  cement  finish 
which  can  be  washed  frequently. 

The  air  should  always  be  fresh  and  without  bad  odor. 
A  sufficient  number  of  lanterns  should  be  provided  to  en- 
able the  necessary  work  to  be  properly  done  during  the  dark 
hours.  The  manure  should  be  removed  twice  daily,  except 
when  the  cows  are  outside  in  the  fields  the  entire  time  be- 
tween the  morning  and  afternoon  milkings.  The  manure 
gutter  must  be  kept  in  a  sanitary  condition.  All  sweeping 
must  be  finished  before  the  grooming  of  the  cows  begins, 
so  that  the  air  may  be  free  from  dust  at  the  time  of  milking. 

There  should  be  an  adequate  supply  of  warm  and  cold 
water  and  the  necessary  wash  basins,  soap,  and  towels. 

3.  Water  Supply. — The  whole  premises  used  for  dairy 
purposes,  as  well  as  the  barn,  must  have  a  supply  of  water 
absolutely  free  from  any  danger  of  pollution  with  animal 
matter  and  sufficiently  abundant  for  all  purposes  and  easy 
of  access. 

4.  The  Cows.  —  No  cows  will  be  allowed  in  the  herd 
furnishing  certified  milk  except  those  which  have  success- 
fully passed  a  tuberculin  test.    All  must  be  tested  at  least 
once  a  year,  by  a  veterinarian  approved  by  the  milk  com- 


60  DAIRY  TECHNOLOGY 

mission.  Any  animal  suspected  of  being  in  bad  health 
must  be  promptly  removed  from  the  herd  and  her  milk  re- 
jected. Do  not  allow  the  cows  to  be  excited  by  hard  driv- 
ing, abuse,  loud  talking,  or  any  unnecessary  disturbance. 

Feed. — Do  not  allow  any  strongly  flavored  food,  like 
garlic,  to  be  eaten  by  the  cows.  When  ensilage  is  fed,  it 
must  be  given  in  only  one  feeding  daily,  and  that  after  the 
morning  milking,  and  the  full  ration  shall  consist  of  not 
more  than  20  pounds  daily  for  the  average-sized  cow. 
When  fed  in  the  fall,  small  amounts  must  be  given  and  the 
increase  to  the  full  ration  must  be  gradual. 

Corn  stalks  must  not  be  fed  until  after  the  corn  has 
blossomed,  and  the  first  feedings  must  be  in  small  amounts 
and  the  increase  must  be  gradual. 

If  fed  otherwise,  ensilage  and  corn  stalks  are  liable  to 
cause  the  milk  to  affect  children  seriously. 

Cleaning. — Groom  the  entire  body  of  the  cow  daily. 
Before  each  milking  wash  the  udder  with  a  cloth  used  only 
for  the  udders,  and  wipe  it  with  a  clean,  dry  towel.  Never 
leave  the  udder  wet,  and  be  sure  that  the  water  and  towel 
are  clean.  The  tail  should  be  kept  clean  by  frequent 
washing.  If  the  hair  on  the  flanks,  tail,  and  udder  is 
clipped  close  and  the  brush  on  the  tail  is  cut  short,  it  will 
be  much  easier  to  keep  the  cow  clean. 

The  cows  must  be  kept  standing  after  the  cleaning  until 
the  milking  is  finished.  This  may  be  done  by  a  chain  or  a 
rope  under  the  neck. 

5.  The  Milkers. — The  milker  must  be  personally  clean. 
He  should  neither  have  nor  come  in  contact  with  any  con- 
tagious disease  while  employed  in  handling  the  milk.  In 
case  of  any  illness  in  the  person  or  family  of  any  employee 
in  the  dairy,  such  employee  must  absent  himself  from  the 
dairy  until  a  physician  certifies  that  it  is  safe  for  him  to 
return. 

In  order  that  the  milk  commission  may  be  informed  as 
to  the  health  of  the  employees  at  the  certified  farms,  the 
commission  has  had  postal  cards  printed  to  be  supplied 
to  the  farms,  and  to  be  filled  out  and  returned  each  week 
by  the  owner,  manager,  or  physician  of  the  farm,  certifying 


CERTIFIED   MILK  6 1 

that  none  are  handling  the  milk  who  are  in  contact  with 
any  contagious  disease. 

Before  milking,  the  hands  should  be  washed  in  warm 
water  with  soap  and  nail  brush  and  well  dried  with  a  clean 
towel.  On  no  account  should  the  hands  be  wet  during 
milking. 

The  milkers  should  have  light-colored,  washable  suits, 
including  caps,  and  not  less  than  two  clean  suits  weekly. 
The  garments  should  be  kept  in  a  clean  place,  protected 
from  dust,  when  not  in  use. 

Iron  milking  stools  are  recommended,  and  they  should 
be  kept  clean. 

Milkers  should  do  their  work  quietly  and  at  the  same 
hour  morning  and  evening.  Jerking  the  teat  increases 
materially  the  bacterial  contamination  of  the  milk  and 
should  be  forbidden. 

6.  Helpers  Other  than  Milkers. — All  persons  engaged  in 
the  stable  and  dairy  should  be  reliable  and  intelligent. 
Children  under  12  should  not  be  allowed  in  the  stable  or 
dairy  during  milking,  since  in  their  ignorance  they  may  do 
harm,  and  from  their  liability  to  contagious  diseases  they 
are  more  apt  than  older  persons  to  transmit  them  through 
the  milk. 

7.  Small  Animals.  —  Cats  and  dogs  must  be  excluded 
from  the  stables  during  the  time  of  milking. 

8.  The  Milk. — All  milk  from  cows  60  days  before  and 
10  days  after  calving  must  be  rejected. 

The  first  few  streams  from  each  teat  should  be  discarded 
in  order  to  free  the  milk  ducts  from  the  milk  that  has  re- 
mained in  them  for  some  time  and  in  which  the  bacteria 
are  sure  to  have  multiplied  greatly.  If  any  part  of  the 
milk  is  bloody  or  stringy  or  unnatural  in  appearance,  the 
whole  quantity  yielded  by  that  animal  must  be  rejected. 
If  any  accident  occurs  in  which  a  pail  becomes  dirty,  or 
the  milk  in  a  pail  becomes  dirty,  do  not  try  to  remove  the 
dirt  by  straining,  but  put  aside  the  pail,  and  do  not  use  the 
milk  for  bottling,  and  use  a  clean  pail. 

Remove  the  milk  from  each  cow  from  the  stable  im- 
mediately after  it  is  obtained  to  a  clean  room  and  strain 


62  DAIRY  TECHNOLOGY 

through  a  sterilized  strainer  of  cheese  cloth  and  absorbent 
cotton. 

The  rapid  cooling  is  a  matter  of  great  importance.  The 
milk  should  be  cooled  to  45°  F.  within  an  hour  and  not 
allowed  to  rise  above  that  as  long  as  it  is  in  the  hands  of 
producer  or  dealer.  In  order  to  assist  in  the  rapid  cooling, 
the  bottles  should  be  cold  before  the  milk  is  put  into  them. 

Aeration  of  milk  beyond  that  obtained  in  milking  is 
unnecessary. 

9.  Utensils.  —  All  utensils  should  be  as  simple  in  con- 
struction  as   possible,  and   so  made   that   they  may   be 
thoroughly  sterilized  before  each  using. 

Coolers,  if  used,  should  be  sterilized  in  a  closed  sterilizer, 
unless  a  very  high  temperature  can  be  obtained  by  the 
steam  sent  through  them. 

Bottling  machines  should  be  made  entirely  of  metal  with 
no  rubber  about  them,  and  should  be  sterilized  in  the  closed 
sterilizer  before  each  milking,  or  bottling. 

If  cans  are  used,  all  should  have  smoothly  soldered  joints, 
with  no  places  to  collect  the  dirt. 

Pails  should  have  openings  not  exceeding  8  inches  in 
diameter,  and  may  be  either  straight  pails,  or  the  usual 
shape  with  the  top  protected  by  a  hood. 

Bottles  should  be  of  the  kind  known  as  "  common  sense" 
and  capped  with  a  sterilized  paraffined  paper  disk,  and  the 
caps  authorized  by  the  commission. 

All  dairy  utensils,  including  the  bottles,  must  be  thor- 
oughly cleansed  and  sterilized.  This  can  be  done  by  first 
thoroughly  rinsing  in  warm  water,  then  washing  with  a 
brush  and  soap,  or  other  alkaline  cleansing  material,  and 
hot  water,  and  thoroughly  rinsing.  After  this  cleansing 
they  should  be  sterilized  by  boiling,  or  in  a  closed  sterilizer 
with  steam,  and  then  kept  inverted  in  a  place  free  from  dust. 

10.  The  Dairy.  —  The  room  or  rooms  where  the  utensils 
are  washed  and  sterilized  and  "the  milk  bottled  should  be 
at  a  distance  from  the  house,  so  as  to  lessen  the  danger  of 
transmitting  through  the  milk  any  disease  which  may  occur 
in  the  house. 

The  bottling  room,  where  the  milk  is  exposed,  should  be 


CERTIFIED  MILK  63 

so  situated  that  the  doors  may  be  entirely  closed  during 
the  bottling  and  not  opened  to  admit  the  milk  nor  to  take 
out  the  filled  bottles. 

The  empty  cases  should  not  be  allowed  to  enter  the 
bottling  room  nor  should  the  washing  of  any  utensils  be 
allowed  in  the  room. 

The  workers  in  the  dairy  should  wear  white  washable 
suits,  including  cap,  when  handling  the  milk. 

Bottles  must  be  capped,  as  soon  as  possible  after  filling, 
with  the  sterilized  disks. 

ii.  Examination  of  the  Milk,  and  Dairy  Inspection. — 
In  order  that  the  dealer  and  the  commission  may  be  kept 
informed  of  the  character  of  the  milk,  specimens  taken  at 
random  will  be  examined  weekly  by  experts  for  the  com- 
mission of  the  department  of  health,  the  use  of  the  labora- 
tories having  been  given  for  that  purpose. 

The  commission  reserves  to  itself  the  right  to  make  inspec- 
tions of  certified  farms  at  any  time,  and  to  take  specimens  of 
the  milk  for  examination,  and  to  impose  fines  for  repeated  or 
deliberate  violations  of  the  requirements  of  the  commission. 

The  commission  also  reserves  the  right  to  change  its 
standards  in  any  reasonable  manner  upon  due  notice  being 
given  to  the  dealers. 

The  expense  of  making  the  regular  milk  reports  and  the 
inspections  are  borne  by  the  dealers.  The  treasurer  of  the 
Medical  Society  of  the  County  of  New  York  will  send 
bills  the  first  of  each  month  for  the  certification  for  the  pre- 
vious month. 

The  monthly  charges,  which  are  intended  to  cover  all 
expenses,  are  as  follows: 

For  daily  output  of  less  than  100  quarts $  8 

For  daily  output  of  from  100  to  200  quarts 10 

For  daily  output  of  from  200  to  500  quarts 12 

For  daily  output  of  over  500  quarts 15 

Where  the  output  of  a  farm  is  sent  to  several  dealers, 
each  dealer  pays: 

For  daily  output  of  less  than  100  quarts $  6 

For  daily  output  of  from  100  to  200  quarts 8 

For  daily  output  of  from  200  to  500  quarts 10 

For  daily  output  of  over  500  quarts 12 


64  DAIRY  TECHNOLOGY 

The  names  of  the  dealers,  with  their  addresses,  are  printed 
on  cards,  and  enclosed  with  the  monthly  bulletin  of  the 
medical  society,  which  is  sent  to  about  1700  physicians. 
For  this  one  dollar  is  charged  each  month. 

Details  of  the  Workings  of  Various  Commissions.  —  The 

maximum  number  of  bacteria  per  cubic  centimeter  allowed 
in  certified  milk  is,  in  the  majority  of  cases,  10,000;  how- 
ever, this  factor  varies  with  different  commissions  from 
5000  to  25,000  in  winter  and  from  10,000  to  50,000  in 
summer. 

The  per  cent  of  fat  in  the  certified  milk  may  vary  from 
3.25  to  5.5.  Some  commissions  require  the  approximate 
per  cent  of  fat  to  be  stated  on  the  bottle.  Only  about 
one-half  the  commissions  have  a  standard  for  solids  not 
fat,  and  in  these  cases  it  varies  from  8  per  cent  to  9.3  per 
cent. 

All  the  commissions  report  little  or  no  difficulty  in  keep- 
ing the  milk  up  to  the  standard. 

The  number  of  quarts  of  milk  handled  daily  under  cer- 
tification of  one  commission  varies  from  120  to  9373. 
The  price  for  which  this  product  is  sold  is  from  one  to 
twelve  cents  per  quart  higher  than  the  price  paid  for 
general  market  milk. 

New  commissions  are  constantly  being  organized,  and 
there  is  a  steadily  increasing  demand  for  certified  milk, 
but  there  is  some  scarcity  of  dairymen  competent  and 
willing  to  undertake  the  task  of  producing  milk  of  such 
high  grade.  The  price  received  for  the  product  hardly 
pays  for  the  great  expense  and  care  necessary  to  keep  up 
to  standard. 

Use  of  Certified  Milk.  —  Certified  milk  will  probably 
never  displace  the  common  market  milk  because  it  is  of 
higher  grade  than  is  necessary  for  general  consumption. 


CERTIFIED  MILK  65 

But  the  value  of  this  milk,  for  the  feeding  of  infants  and 
others  whose  digestive  systems  are  not  strong,  is  generally 
recognized. 

The  greatest  and  probably  the  only  objection  to  the  use 
of  certified  milk  is  its  greater  cost,  but  this  disadvantage 
is  offset  by  the  following  advantages: 

1.  Certified  milk  is  free  from  pathogenic  organisms. 

2.  It  is  low  in  total  bacteria  and  especially  so  in  un- 

desirable species. 

3.  The  physical  and  chemical  properties  of  the  milk 

are  uniform  from  day  to  day. 

4.  Cleanliness  and  cold  are  the  only  preservatives 

used. 

5.  It  is  a  safe  food  for  any  one. 

Production  of  Certified  Milk.  —  A  model  dairy  farm 
for  the  production  of  certified  milk  is  equipped  with  a 
well  lighted,  well  ventilated,  tight  barn,  having  few  beams 
and  braces  to  catch  dust,  a  cement  floor,  mangers,  and 
plastered  walls,  so  that  the  whole  place  may  be  cleaned 
easily  and  quickly  each  day. 

All  cows  are  annually  tested  for  tuberculosis,  and  any 
cow  showing  any  indications  of  disease  or  abnormality  of 
any  kind  is  isolated  and  her  milk  rejected.  The  cows 
are  daily  curried  or  brushed,  or  cleaned  with  a  vacuum 
cleaner;  the  hair  on  flank  and  udder  is  clipped  short; 
and  the  greatest  care  taken  to  have  the  animal  perfectly 
clean.  Before  milking,  all  cows  are  made  to  stand  on 
their  feet,  and  a  chain  is  run  under  their  necks  along  the 
stanchions  to  prevent  them  from  lying  down  again  before 
being  milked;  then  the  udder  and  flank  are  washed  with 
clean  warm  water. 

No  cleaning,  brushing  or  disturbing  of  bedding  and  hay 


66  DAIRY  TECHNOLOGY 

is  permitted  within  an  hour  before  milking  time,  so  that 
the  air  may  be  free  from  dust  when  the  milk  is  drawn. 

At  milking  time  the  milker,  dressed  in  a  clean  white 
suit,  approaches  the  cleaned  cow  with  a  steam-sterilized, 
covered  milk  pail,  sits  well  back  from  the  cow  to  avoid 
brushing  her  with  his  arms. or  head,  and  holds  the  pail  at 
an  angle  to  prevent  dirt  from  dropping  into  the  milk. 
The  milker's  hands  are  clean  and  he  touches  no  part  of 
the  cow  but  her  teats;  the  fore  milk  is  drawn  into  a  separ- 
ate receptacle  and  discarded. 

Having  completed  the  milking  of  one  cow,  the  milker 
carries  his  pail  to  the  milk  room,  hands  it  to  the  person 
in  charge,  who  weighs  the  milk,  wipes  the  top  of  the  pail 
with  a  damp  cloth  and  pours  the  milk  over  an  enclosed 
cooler.  During  this  tune,  the  milker  washes  his  hands 
and  wipes  them  on  a  clean  towel,  then  returns  to  milk 
another  cow. 

In  the  milk  room  the  milk  is  run  over  a  cooler  into  sterile 
cans,  then  removed  to  the  bottling  room  and  put  into 
sterile  bottles,  capped  and  packed  in  ice  ready  for  de- 
livery. 

This  milk  reaches  the  consumer  within  less  than  24  hours 
from  the  tune  it  is  drawn  and  at  a  temperature  of  50°  F. 
or  less. 

INSPECTED  MILK. 

Milk  of  this  grade  is  general  market  milk  produced  on 
average  farms,  but  subject  to  supervision  of  inspectors. 
This  grade  of  milk  is  usually  of  sufficiently  high  quality  for 
general  use  in  the  household. 


CHAPTER  VH. 

PASTEURIZED  MILK. 

PASTEURIZATION  of  milk  in  the  city  milk  plant  is  becom- 
ing very  general,  so  that  frequently  the  inspected  and 
ordinary  market  milk  are  subjected  to  this  process.  In 
some  instances  this  grade  of  milk  wholly  displaces  the 
inspected  milk.  The  advisability  of  adopting  pasteuriza- 
tion instead  of,  and  in  addition  to,  close  inspection  as  a 
means  of  improving  our  milk  supply  is  a  much-mooted 
question. 

The  problem  of  quickly  perfecting  the  milk  supply  of  a 
city  is  a  very  difficult  one.  If  stringent  laws  were  enacted 
and  immediately  put  into  force  (for  example,  a  law  pro- 
hibiting the  sale  of  milk  from  dairies  scoring  under  80  per 
cent  by  the  score  card)  there  would  be  a  milk  famine  in 
many  cities.  Hence  it  is  evident  that  improvement  at  the 
place  of  production  cannot  be  made  in  a  day  or  a  week; 
but  when  it  does  come,  it  will  be  a  gradual  evolution  stim- 
ulated by  education  and  public  sentiment,  and  by  paying 
the  producer  a  higher  price  for  his  product.  Therefore, 
quantities  of  milk  produced  under  conditions  of  an  un- 
known degree  of  sanitation  must  be  admitted  to  the  market. 
In  order  to  improve  the  milk  of  doubtful  character,  it  is 
recommended  that  all  such  milk  be  properly  pasteurized. 
It  is  an  undisputed  fact  that  certified  milk  is  better  than 
pasteurized  milk,  but  under  existing  conditions  it  is  some- 
times necessary  to  choose  between  pasteurized  milk  and  no 
milk. 

67 


68  DAIRY  TECHNOLOGY 

ALLEGED  DISADVANTAGES  OF  PASTEURIZATION. 

Those  opposed  to  the  use  of  pasteurized  milk  for  city 
milk  supply,  find  the  following  objections  to  this  product: 

1.  It  promotes   carelessness   and   discourages   efforts 

to  produce  clean  milk. 

2.  It  produces  chemical  changes  in  the  milk  which 

render  it  less  easily  digested. 

3.  Desirable  lactic-acid  bacteria  are  killed,  while  some 

undesirable  types  (spore  formers J  are  not. 

4.  Germs  are  killed,  but  their  toxic  by-products  re- 

main. 

5.  Pasteurization  covers  defects  in  milk. 

6.  It  affects  flavor  and  creaming  property. 

7.  The  cost  of  pasteurization  is  considerable. 

i.  Promotes  Carelessness. — It  is  claimed  that  pasteur- 
ization will  encourage  the  producer  and  handler  of  milk  to 
be  careless  and  use  unclean  methods,  believing  great  care 
unnecessary  because  the  milk  is  going  to  be  "cooked"  any- 
way. The  dealer  may  be  careless  in  regard  to  the  tempera- 
ture at  which  the  pasteurized  milk  is  held  and  permit  the 
spores  to  vegetate  and  multiply  to  such  an  extent  that 
the  milk  would  be  a  very  dangerous  food.  If  pasteurized 
milk  be  placed  in  unclean  bottles  and  the  organisms  be  per- 
mitted to  multiply,  by  keeping  it  too  long  a  time,  such  milk 
probably  would  be  more  unhygienic  than  the  raw  product. 

In  reply  to  this  it  may  be  said  that  pasteurization  is  a 
corrective  measure  and  this  is  never  as  satisfactory  as  a 
preventive  measure.  In  many  cities  milk  is  inspected  by 
the  health  authorities  before  pasteurization,  and  if  found 
to  be  very  unsanitary  is  condemned.  It  is  to  the  interest 
of  the  dealer  to  have  milk  in  good  condition  before  pasteuri- 
zation, because  it  insures  a  product  having  better  flavor 


PASTEURIZED   MILK  69 

and  keeping  qualities  than  that  from  unsanitary  milk. 
Milk  of  doubtful  sanitary  qualities  is  an  existing  evil,  and 
pasteurization  is  a  present  and  efficient  remedy. 

2.  Produces  Chemical  Changes  in  Milk. — The  chemical 
changes  wrought  in  milk  by  the  heating  process  are  said 
to  render  milk  less  digestible  and  to  cause  rickets  and  scurvy 
in  children. 

The  pasteurization  of  milk  for  adults,  however,  can  be 
no  more  objectionable  than  the  cooking  of  meat.  It  is 
sterilization  and  high  temperature  pasteurization  which 
cause  changes  in  milk,  while  on  the  other  hand,  a  tempera- 
ture of  145°  F.  for  twenty  minutes  (as  is  commonly  used 
in  commercial  pasteurization)  does  not  appreciably  affect 
its  physical  and  chemical  properties. 

Nature  did  not  intend  that  milk  should  be  cooked,  neither 
did  nature  intend  that  milk  should  be  exposed  to  bacterial 
contamination  and  unfavorable  surroundings,  and  be  al- 
lowed to  undergo  fermentative  changes  for  a  day  or  two 
before  being  consumed. 

An  excessively  high  temperature,  especially  if  prolonged, 
will,  it  is  true,  decompose  some  of  the  proteins,  diminish 
the  organic  phosphorous,  increase  the  inorganic  phos- 
phorous, precipitate  the  calcium  and  magnesium  salts  and 
phosphates,  expel  most  of  the  carbon  dioxide,  partially 
caramelize  the  lactose,  cause  a  coalescence  of  some  of  the 
fat  globules,  and  coagulate  some  of  the  serum  albumin. 
Heat  also  destroys  the  enzymes  which,  according  to  some 
authors,  aid  in  digestion  and  metabolism. 

3.  Desirable    Lactic-acid    Bacteria    are     Killed,    while 
Some     Undesirable     Types    are    not.  —  Since    lactic-acid 
organisms  are  not  spore  producers  they  have  as  low  a 
thermal  death  point  as  the  pathogenic  organisms,  and  are 
killed    by    pasteurization.     In   raw   milk   the   lactic-acid 


70  DAIRY  TECHNOLOGY 

bacteria  inhibit  the  growth  of  the  putrefactive  organisms, 
but  in  pasteurized  milk  the  spore-producing  putrefactive 
bacteria  have  a  clearer  field  for  growth,  and  may  develop 
poisonous  substances  without  changing  the  appearance  or 
physical  condition  of  the  milk. 

Ayers  and  Johnson1  have  found  that  milk  pasteurized 
under  commercial  conditions  sours  because  of  the  develop- 
ment of  lactic-acid  bacteria  which,  on  account  of  their 
high  thermal  death  point,  survive  pasteurization;  and  per- 


FIG.  2.  —  Combination  heating,  holding,  and  cooling  tank. 
(Circular  184,  Dairy  Division,  U.  S.  Dept.  of  Agr.) 

haps,  in  some  cases,  because  of  subsequent  infection  with 
acid-forming  bacteria,  during  cooling  and  bottling.  The 
nature  of  the  souring  of  efficiently  pasteurized  milk  (140° 
F.  for  30  minutes  or  160°  F.  for  a  few  seconds)  is  similar 
to  that  of  clean  raw  milk.  In  both  classes  of  milk,  accord- 
ing to  the  same  authorities,  the  alkali  or  inert  bacteria 
constitute  the  largest  group,  the  lactic  acid  next,  and  the 
peptonizers  the  smallest  group.  As  these  milks  are  held, 
the  lactic-acid  group  gains  ascendency  over  the  other  two 
classes,  while  the  peptonizers  remain  the  smallest  group. 
1  U.  S.  Dept.  of  Agr.,  Bu.  An.  Ind.,  Bui.  126. 


PASTEURIZED   MILK  71 

The  cleaner  the  raw  milk,  the  smaller  is  the  percentage  of 
lactic-acid  bacteria.  Also,  the  more  efficient  the  pasteuriza- 
tion, the  smaller  is  the  percentage  of  lactic-acid  organisms. 
The  number  of  peptonizers,  in  a  good  grade  of  commercially 


'Outgoing  Milk 

FIG.  3.  —  Holding  tank  with  automatic  emptying  device. 
(Circular  184,  Dairy  Division,  U.  S.  Dept.  of  Agr.) 

pasteurized  milk,  on  the  initial  count  and  on  succeeding 
days,  is  approximately  the  same  as  in  a  clean  raw  milk 
held  at  the  same  temperature.  In  milk  heated  for  30 
minutes  at  140°  F.,  it  was  found  that  about  five  per  cent 
of  the  acid  producers  resisted  the  heating. 


72 


DAIRY   TECHNOLOGY 


4.   Toxic  Properties  Remain  in  Milk.  —  Many  bacterial 
toxines  are  destroyed  by  heat,  but  others  are  not;  hence  it 

is  argued  that  pasteurized 

Cold  Raw 


Milk 1—' 

V    Outlet 


Outlet  for  Cold 
Pasteurized  MTllr 


milk  may  still  be  an  un- 
wholesome product. 

The  existence  of  toxines 
in  market  milk  has  been 
largely  inferred,  not  dem- 
onstrated. If  heat-resist- 
ing toxines  exist  in  milk, 
the  raw  product  will  be 
just  as  toxic  as  the  heated, 
and  probably  more  so,  be- 
cause heating  would  stop 
the  development  of  the 
toxines. 

5.  Pasteurization  Covers 
Defects  in  Milk.  —  Pas- 
teurization may  be  used 
to  hide  the  age  of  milk, 
so  that  the  surplus  from 
one  day  may  be  disposed 
of  on  the  following  day. 
By  re-pasteurization,  milk 
might  be  held  for  a  long 

without  showing  its 


cooler.     (Circular  184,  Dairy  Division,          j  j... 

aged  condition. 


FIG.  4.  —  Sectional  view  of  a  regenerative 
cooler.     (Circular  i* 
U.  S.  Dept.  of  Agr.) 

The  re-pasteurization  of 

milk,  however,  is  prohibited  by  law  in  some  cities.  Such  a 
practice  is  not  conducive  to  securing  a  high-grade  product  and, 
so  far  as  known,  does  not  obtain  under  commercial  conditions. 
6.  Affects  Flavor  and  Creaming  Property.  —  When  milk 
has  been  subjected  to  a  high  temperature  the  cream  rises 


PASTEURIZED   MILK 


73 


more  slowly  and  less  completely  than  it  does  in  the  case 
of  unheated  milk.  The  viscosity  of  the  milk  is  lessened 
and  the  milk  appears  to  have  a  lower  fat  content.  Heated 
milk  has  a  characteristic,  so-called,  cooked  flavor,  which 
is  objectionable  to  many  people. 

Although  pasteurization  inhibits  cream  from  rising, 
the  amount  of  cream  in  the  milk  is  not  decreased.  When 
customers  learn  to  know  this  fact,  pasteurization  is  not 
so  much  objected  to.  As  the  process  of  pasteurization 


Supply  Tank 

Pasteurizer  1  1 

n^ 

* 

JJ 

<  —  Holding 
Tank 

/ 

/ 

. 

Milk 
Pump->C 

\—  ^-/c    Bottle 
juuuuuj      Filler 

J    y|                       a  h  —  ReceiyinglTank 

FIG.  5.  —  General  arrangement  of  machinery  for  pasteurizing  milk. 
(Circular  184,  Dairy  Division,  U.  S.  Dept.  of  Agr.) 

is  carried  on  under  commercial  conditions  at  the  present 
time,  the  creaming  property  of  the  milk  is  affected  but 
little,  if  at  all,  and  no  cooked  flavor  can  be  detected  after 
the  milk  has  been  cooled  and  held  a  few  hours.  Some 
people  prefer  the  flavor  of  heated  milk  to  that  of  unheated. 

7.  Cost  of  Pasteurization.  —  The  cost  of  pasteurizing 
milk  for  city  supply  is  difficult  to  state.  This  would  vary 
with  the  amount  to  be  pasteurized,  the  kind  of  help,  the 
method  of  pasteurization,  the  efficiency  of  boiler  and  other 
machinery,  and  the  handiness  of  the  plant. 

Generally  speaking,  i  pound  of  steam  heats  1000  pounds 


74 


DAIRY  TECHNOLOGY 


or  500  quarts  of  milk  i°  F.  It  is  necessary  to  heat  the 
milk  about  100°  F.  100  pounds  of  steam  are  then  re- 
quired to  heat  1000  pounds  of  milk  100°  F.  As  i  pound 
of  coal  produces  about  six  pounds  of  steam,  about  seven- 
teen pounds  of  coal  are  necessary  to  pasteurize  the  1000 
pounds  of  milk.  The  cost  of  this  coal  at  $6.00  per  ton, 
is  about  5.1  cents.  It  costs  an  equal  amount,  5.1  cents, 
to  bring  the  temperature  of  the  boiler  up  to  the  point  of 


FIG.  6.  —  View  of  C.  P.  pasteurizing  machine. 

steam  pressure.  The  cost  of  cooling  this  amount  of  milk 
may  be  estimated  at  50  cents.  If  the  pasteurizing  ma- 
chinery costs  $2000  the  depreciation  of  same  may  be 
estimated  at  $i  per  day;  thus  the  machinery  should  last 
10  years.  The  interest  at  7  per  cent  amounts  to  about 
forty  cents  per  day.  In  addition  it  costs  $1.50  for  one- 
half  day's  labor.  The  total  cost  of  pasteurizing  500  quarts 
of  milk  100°  F.  is  then  about  $3.50  per  day,  or  0.7  cent 
per  quart. 


PASTEURIZED   MILK  75 

ADVANTAGES  OF  PASTEURIZATION. 

The  following  arguments  are  presented  in  favor  of  the 
use  of  pasteurized  milk: 

1.  Protection  from  pathogenic  bacteria  occasionally 

found  in  milk. 

2.  A  decrease  in  the  total  number  of  bacteria. 

3.  Aids  in  the  preservation  of  milk. 

1.  Protection  from   Pathogenic    Bacteria.  —  Epidemics, 
such  as  typhoid  fever,  diphtheria  and  scarlet  fever,  are 
on  record  as  having  been  transmitted  through  milk,  as 
has  already  been  mentioned  in  Chapter  IV.     Several  in- 
vestigations of  market  milk  have  revealed  the  presence 
of  the  tubercle  bacillus  in  approximately  10  per  cent  of 
the  dairies.    There  is  strong  evidence  showing  that  these 
diseases,  under  certain  conditions,   may  be   transmitted 
to  the  consumer.     This  danger  may  be  obviated  and  the 
public  protected  by  efficient  pasteurization  of  the  entire 
city   milk   supply.     All   of    these   pathogenic   germs    are 
destroyed  by  pasteurization,  as  they  are  not  spore  forming. 

2.  Decreases  the  Total  Number  of  Bacteria.  —  Milk  as 
a  food  is  of  greatest  importance  to  the  welfare  of  chil- 
dren, and  the  decrease  of  infant  mortality  is  one  of  the 
virtues  claimed  for  pasteurized  milk. 

We  have  already  seen  in  a  previous  chapter  how  the 
Nathan  Straus  milk  depots  alleviated  infantile  gastro-mesen- 
teric  illness,  and  how  the  installation  of  a  pasteurizing  plant 
at  the  Children's  Home  on  Randall  Island,  New  York  City, 
decreased  the  annual  death  rate.  Many  similar  instances 
of  the  benefits  of  milk  pasteurization  may  be  mentioned. 

Variot  distributed  for  12  years  in  the  poorest  quarters 
of  Paris  about  400,000  bottles  of  pasteurized  milk  to  more 
than  3000  infants,  and  reports  that  there  was  never  a  single 


76  DAIRY  TECHNOLOGY 

case  of.  scurvy  or  rachitis  among  the  consumers  of  the 
milk,  and  that  the  infants  maintained  their  health  and 
normal  development  on  this  diet. 

Park  &  Holth  of  New  York  City  found  (1902-1903) 
that  infants  fed  on  pasteurized  milk  thrived  much  better 
than  those  fed  on  raw  milk.  They  experimented  on  50 
babies  from  the  tenement  houses,  and  divided  them  into 
two  equal  lots.  They  were  all  fed  on  milk  modified  at  the 
Straus  milk  depot.  They  were  treated  the  same,  excepting 
one  lot,  who  were  fed  milk  pasteurized  30  minutes  at 
165°  F.,  and  the  other  half  were  fed  the  same  kind  of  milk 
unheated.  The  pasteurized  milk  in  the  morning  con- 
tained 1000  germs  per  cubic  centimeter,  while  the  raw 
milk  contained  1,200,000  per  cubic  centimeter,  and  the 
pasteurized  milk  contained  in  the  afternoon  of  the  same  day 
50,000  germs  per  cubic  centimeter  while  the  raw  milk 
contained  20,000,000  per  cubic  centimeter. 

The  investigators  made  the  following  remarks : 

"  Within  i  week,  20  of  the  27  infants  put  on  the  raw  milk, 
suffered  from  moderate  or  severe  diarrhea,  while  during 
the  same  time,  only  5  cases  of  moderate  and  none  of 
severe  diarrhea,  occurred  in  those  taking  pasteurized  milk. 
Within  a  month,  8  of  the  27  had  to  be  changed  from  raw, 
back  to  heated  milk,  because  of  their  continued  illness.  7, 
or  25  percent,  did  well  all  summer  on  raw  milk.  On  the 
other  hand,  of  those  receiving  the  pasteurized  milk,  75  per- 
cent remained  well  or  nearly  so  all  summer,  while  25  per- 
cent had  one  or  more  attacks  of  severe  diarrhea.  There 
were  no  deaths  in  either  group  of  cases." 

Berlioz,  in  Grenoble,  France,  distributed  from  1894  to 
1897  sterilized  milk  (heated  under  pressure)  for  infant  feed- 
ing, and  found  an  average  death  rate  of  27.9  per  1000  for 
those  using  the  sterile  product,  as  compared  with  a  death 
rate  of  69.3  per  1000  for  infants  fed  on  raw  milk. 


PASTEURIZED    MILK  77 

3.  Pasteurized  Milk  Keeps  Longer.  —  Milk  is  com- 
monly bought  in  quantities  sufficiently  large  to  supply  the 
consumer  for  24  hours.  During  hot  weather,  even  a  good 
quality  of  inspected  milk  may  become  unfit  for  use  in 
24  hours,  unless  a  very  low  temperature  is  maintained. 
Among  the  poorer  classes  and  even  among  the  middle 
classes,  ice  is  too  expensive  to  use  for.  cooling  purposes. 
But  because  of  the  improved  keeping  qualities  of  pasteu- 
rized milk,  the  consumer  is  able  to  keep  this  grade  of  milk 
in  a  hygienic  condition  for  a  longer  time  than  the  regular, 
inspected  raw  milk  can  be  kept. 

Because  of  the  prolonged  keeping  quality,  the  dealer 
has  fewer  complaints  from  his  customers,  and  he  has 
less  loss  through  the  souring  of  milk  before  it  can  be 
delivered.  Hence  pasteurization  is  of  economic  import- 
ance. 

Pasteurization  of  Milk  Increasing.  —  That  pasteuriza- 
tion is  being  adopted  by  more  and  more  cities  and  dealers, 
speaks  strongly  in  favor  of  this  grade  of  milk.  In  the  year 
1900,  only  5  per  cent  of  New  York  City's  milk  supply  was 
pasteurized;  in  1909,  25  per  cent  was  pasteurized,  and 
probably  33  per  cent  now  undergoes  heating.  The  city 
board  of  health  has  ruled  that  after  January  i,  1912,  all 
milk,  except  that  produced  under  certain  conditions,  shall 
be  pasteurized.  In  Boston  33  per  cent  of  the  milk  is  pas- 
teurized; in  Chicago  50  per  cent,  and  in  Milwaukee  about 
seventy-five  per  cent. 

Official  Supervision  of  Pasteurization.  —  H.  C.  Campbell1 
has  shown  that,  in  cities  where  milk  pasteurization  is  not 
under  official  supervision,  commercial  pasteurization  can- 
not be  relied  upon  as  a  means  of  destroying  pathogenic 
bacteria  in  milk. 

1  U.  S.  Dept.  of  Agr.,  Bu.  An.  Ind.,  An.  Kept.,  1909. 


78  DAIRY  TECHNOLOGY 

Russell  and  Hastings,1  Schroeder2  and  others  have  shown 
that  a  temperature  of  140°  F.,  for  20  minutes,  is  sufficient 
to  kill  tubercle  bacilli  in  milk.  Schroeder  tells  us  that: 

"  The  simplest,  the  least  expensive,  and  the  most  effi- 
cient available  expedient  through  which  the  public  can  be 
protected  against  bovine  tubercle  bacilli  and  other  viruses 
that  may  be  disseminated  with  milk  is  pasteurization." 

He  also  states  that,  until  commercial  pasteurization  has 
been  placed  under  official  supervision,  home  pasteurization 
should  be  employed  as  the  best  solution  to  the  milk  problem. 

Inefficiency  of  pasteurization  under  commercial  con- 
ditions is  usually  due  to  ignorance  or  carelessness.  The  de- 
gree of  heat  and  the  time  of  exposure  that  are  necessary  to 
improve  the  keeping  quality  of  milk  also  kill  all  pathogenic 
organisms.  The  finding  of  contagious  disease  producing 
germs  in  milk  is  an  indication  that  the  dealer  has  not  even 
accomplished  his  special  object  of  improving  the  keeping 
properties  of  his  milk.  The  dealers,  as  well  as  the  patrons, 
suffer  because  of  this  lack  of  efficient  pasteurization. 

The  movement  for  the  adoption  of  compulsory  official 
supervision  of  all  milk  for  city  supply  is  gathering  momen- 
tum and  producing  most  satisfactory  results.  In  cities 
where  such  supervision  is  properly  enforced,  the  pasteurized 
milk  can  be  relied  upon. 

Laws  and  Ordinances  Pertaining  to  Pasteurization.  — 
There  has  been,  during  the  past  few  years,  considerable 
legislation  pertaining  to  pasteurization.  New  York  City 
has  recently  added  the  following  rules  to  its  sanitary  code: 

i.  Pasteurization  must  be  carried  out  under  a  permit 
therefor  issued  by  the  board  of  health,  in  addition  to  the 
usual  permit  for  milk. 

1  Outlines  of  Dairy  Bacteriology. 

2  U.  S.  Dept.  of  Agr.,  Bu.  An,  Ind.,  An.  Kept.,  1909. 


PASTEURIZED   MILK  79 

2.  Only  such  milk  or  cream  shall  be  regarded  as  pasteur- 
ized as  has  been  subjected  to  a  process  in  which  the  tem- 
perature and  exposure  conform  to  one  of  the  following: 

No  less  than  158  degrees  F.  for  at  least  3  minutes. 
No  less  than  155  degrees  F.  for  at  least  5  minutes. 
No  less  than  152  degrees  F.  for  at  least  10  minutes. 
No  less  than  148  degrees  F.  for  at  least- 15  minutes. 
No  less  than  145  degrees  F.  for  at  least  18  minutes. 
No  less  than  140  degrees  F.  for  at  least  20  minutes. 

3.  The  milk  after  pasteurization  must  be  at  once  cooled 
and  placed  in  sterile  containers  and  the  containers  sealed. 

4.  All  pasteurized  milk  must  be  delivered  to  the  con- 
sumer  in   sealed    containers   which   are   plainly   labeled, 
"  Pasteurized."     The  label  must  also  bear  the  date  and 
hour  when  the  pasteurization  of  the  milk  was  completed, 
the  degree  of  the  heat  employed,  the  length  of  time  exposed 
to  the  heat  and  the  number  of  the  pasteurization  permit 
issued  by  the  board  of  health. 

5.  Pasteurized  milk  must  be  delivered  to  the  consumer 
within  24  hours  of  the  pasteurization. 

6.  No  milk  shall  be  pasteurized  a  second  time. 

Home  Pasteurization.  —  Milk  may  be  efficiently  pas- 
teurized in  the  home,  if  the  person  doing  the  work  has  a 
thorough  knowledge  of  the  process.  It  is  not  safe,  how- 
eve,  to  leave  it  to  irresponsible  servants. 

The  bottle  of  milk  as  it  is  received  from  the  delivery- 
man  may  be  immersed  in  water  (not  hot  enough  to  break 
the  bottle)  to  its  neck  in  a  cooking  vessel.  The  milk  should 
first  be  well  shaken  to  insure  uniform  heating.  If  thick 
cream  be  left  on  top  of  the  milk,  it  will  not  circulate  well 
and  will  not  be  so  quickly  nor  efficiently  heated.  A  dairy 
thermometer  may  be  stuck  through  the  pulp  cap,  the  vessel 
set  upon  the  stove  and  the  milk  heated  to  the  necessary 
temperature.  The  milk  may  be  cooled  slowly  in  this  vessel 
by  occasionally  adding  a  small  quantity  of  cold  water 
until  the  milk  is  cooled  to  the  temperature  of  the  water. 


CHAPTER   VHI. 

'  MODIFIED  MILK. 

Use  of  Modified  Milk. —  The  normal  healthy  adult 
does  not  need  this  class  of  milk.  But  the  ability  of  the 
infant,  the  invalid,  and  persons  suffering  from  indigestion, 
is  at  times  such  that  normal  milk  may  not  be  properly 
digested  and  assimilated.  Hence,  it  becomes  necessary 
to  modify  this  natural  product  to  meet  the  requirements 
of  these  individuals. 

Although  the  quantity  of  this  grade  of  milk  consumed, 
like  certified  milk,  is  very  small  compared  with  the  great 
bulk  of  regular  market  milk,  it  is  of  great  importance, 
because  of  its  extensive  use  for  infants. 

Digestibility  of  Modified  Milk.  —  The  modification  of 
milk  for  infant  feeding  owes  its  origin  and  present  use  to 
the  fact  that  normal  cow's  milk  frequently  cannot  be 
properly  digested  by  an  infant.  This  is  due,  first,  to 
cows'  milk  having  a  different  composition  from  that  of 
human  milk;  and,  secondly,  to  the  fact  that  some  infants 
have  weak  digestive  systems  and  therefore  require  milk 
of  special  composition.  Therefore,  it  becomes  necessary 
so  to  alter  the  composition  and  the  physical  and  chemical 
properties  of  the  milk  that  it  may  be  properly  digested 
and  assimilated. 

It  is  possible  that  the  casein  in  cows'  milk  is  too  often 
held  to  be  responsible  for  digestive  troubles  in  infants. 

Huebner,1  Keller  and  Czerny  in  Europe,  and  Brenne- 

1  Hygienic  Laboratory,  Bui.  56. 
80 


MODIFIED  MILK  8l 

mann1  and  Walls  in  this  country  have  shown  that,  in  itself, 
cows'  milk  proteid  is  almost  as  easily  digested  by  infants 
as  is  that  of  human  milk.  Czerny  and  Keller  have  shown 
that  it  is  the  fat,  not  the  proteid;  that  is  the  main  cause  of 
digestive  disturbances. 

Since  there  are  so  many  infants  that,  for  various  reasons, 
are  artificially  fed,  the  proper  modification  of  milk  to 
meet  their  needs  is  a  very  delicate  and  important  matter. 
The  milk  provided  by  nature  for  the  infant  is  usually  the 
best  food;  hence,  in  artificial  feeding,  the  aim  is  to  imi- 
tate this  product  as  closely  as  possible.  It  is  therefore 
necessary  to  have  an  exact  knowledge  of  the  composition 
and  characteristics  of  human  milk. 

Human  Milk.  —  The  first  few  days  after  parturition, 
colostrum  is  secreted  as  in  the  case  of  lower  animals.  This 
is  characterized  by  a  higher  proteid  and  mineral  content, 
and  a  lower  fat  and  sugar  content  than  the  normal  milk, 
and  in  addition  contains  numerous  colostrum  corpuscles, 
which  are  four  to  five  times  as  large  as  the  normal  fat 
globules. 

The  composition  of  human  colostrum  milk,  according  to 
Pfeiffer,  is 

Proteid 5  •  71 

Fat 2 . 04 

Sugar 3 . 74 

Salts  or  minerals 0.25 

Water. 88.23 

Normal  Human  Milk  Compared  with  Cows'  Milk.  — 

The  composition  of  human  milk  has  not  been  very 
thoroughly  investigated,  but  an  average  of  the  most  recent 
analyses  by  some  of  our  best  authorities  is  shown  in  the 

1  Hygienic  Laboratory,  Bui.  56. 


82 


DAIRY  TECHNOLOGY 


following  table,  together  with  the  average  composition  of 
cows'  milk. 


Human. 

Cow. 

Fat 

400 

3tjn 

Proteid 

I     ^O 

400 

Sufirar 

7    OO 

4f  Q 

Salts  (ash) 

O    2O 

O    7$ 

Water 

8?    3O 

87    2< 

Calories  per  kilogram    (or  2.2  Ibs.) 

100.00 
7IO    ^O 

IOO.OO 

726  oo 

It  may  be  noted  in  the  table  that  the  main  difference 
in  the  composition  of  the  two  milks  is  that  human  milk 
is  lower  in  proteids  and  ash  and  higher  in  sugar  than  is 
cows'  milk. 

According  to  Koenig,  the  proportion  of  lactalbumin 
to  casein  is  as  5  to  4  in  human  milk.  This  is  a  marked 
variation  from  the  proportion  of  these  constituents  in 
cows'  milk,  which  latter  is  about  one  to  three. 

When  dilute  acids  are  added  to  normal  human  milk  a 
light  flocculent  precipitate  is  formed  instead  of  the  solid 
curd  formed  in  cows'  milk.  Rennet  extract,  although  it 
quickly  coagulates  cows'  milk  (when  under  proper  con- 
ditions) does  not  materially  affect  human  milk. 

Food  Requirements  of  Infants.  —  The  diet  of  adult 
man  has  been  a  subject  of  study  for  many  years,  but  the 
nutritive  requirements  of  infants  have  received  detailed 
and  thorough  attention  only  during  the  past  few  years. 
0.  Heubner1  of  Berlin  was,  so  far  as  known,  the  first  in- 
vestigator along  this  line,  but  he  now  has  many  followers.2 

1  Heubner  —  Die  Energiebilanz  des  Sauglings.     Zeitschrift  f.  diate  u. 
physik.     Theraouem,  1901.     Vol.  V.  —  Reviewed  in  Hygienic  Lab.  Bui.  56. 

2  Bren  and  Walls  —  Am.  Journal  Med.  Ass'n.,  1907,  Vol.  XLVIII. 


MODIFIED  MILK  83 

He  calculated  the  bodily  needs  of  the  infant  on  the  calorie 
basis,  and  finds  the  following  daily  requirements  per 
kilogram  (about  2.2  pounds)  of  body  weight:  First  week 
in  life,  60  calories  (i  calorie  being  the  amount  of  heat 
required  to  raise  i  kilogram  of  water  i°  C.);  first  3  months, 
100  calories;  second  3  months,  100  to  90  calories;  third 
and  fourth  3  months,  80  calories  per  kilogram  of  body 
weight  per  day.  The  maximum  and  minimum  require- 
ments being  100  to  70  calories  respectively,  when  these 
limits  were  overstepped  unfavorable  results  ensued. 

In  addition  to  the  required  heat  units,  the  infants'  food 
must  contain  the  proper  proportion  of  the  various  classes 
of  nutrients  —  proteid,  carbohydrates  and  fat,  and  min- 
eral matter.  The  proper  ratio  of  the  different  constituents 
will  vary,  depending  upon  the  following  conditions:  in- 
dividuality, age,  activity  of  the  infant,  amount  of  fresh 
air  received  and  other  general  conditions  of  living. 

Manner  of  Modifying  Milk.  —  The  milk  prescribed 
shall  be  of  such  quality  and  quantity  (above-named  con- 
ditions considered)  as  to  furnish  the  energy  quotients  re- 
quired, and  no  more,  and,  at  the  same  time,  contain  the 
proper  proportionate  amount  of  each  of  the  different  food 
nutrients. 

To  calculate  the  number  of  calories  in  the  modified 
milk  the  following  figures  may  be  used: 

i  gram  of  butter  fat  produces  9.3  calories. 

i  gram  of  proteid  produces  4.1  calories. 

i  gram  of  carbohydrate  produces  4.1  calories. 

To  insure  the  proper  proportionate  amounts  of  the 
different  nutrients  and  make  the  modified  milk  resemble 
in  composition  human  milk,  it  is  necessary  to  reduce  the 
amount  of  casein  in  cows'  milk,  increase  the  amount  of 


84 


DAIRY  TECHNOLOGY 


sugar,  and  still  maintain  the  other  constituents  at  normal. 
This  may  be  done  by  mixing,  in  the  proper  proportion, 
liquids  of  known  composition,  for  example,  cream,  whey 
(containing  added  milk  sugar)  and  distilled  water  as 
follows : 

To  make  100  pounds  modified  milk: 


Fat. 

Casein. 

Albumin. 

Sugar. 

Ash. 

20   Ibs.    cream    (18   per 
cent  fat)  . 

Lbs. 
3  60 

Lb. 
o  <o 

Lb. 
O'  I? 

Lbs. 
I  .OO 

Lb. 
o.  14 

70   Ibs.    whey    (8.5    per 
cent  milk  sugar)  
lolbs.  distilled  water.  .  . 
100  Ibs.  containing  

0.14 
o.oo 

3-74 

0.03 
o.oo 

0.53 

0.49 

o.oo 
0.64 

5-9S 
o.oo 

6.95 

0.49 

0.00 

0.63 

The  composition  of  this  modified  milk  approaches, 
very  closely,  that  of  human  milk. 

In  large  cities  there  are  special  laboratories  in  which 
modified  milk  is  prepared.  Calculated  tables  are  con- 
sulted, so  that  any  quantity  of  fresh  modified  milk  can 
quickly  be  made.  The  physician  prescribes  milk  of  a 
certain  composition.  This  prescription  can  then  be  taken 
to  the  laboratory,  and  the  modified  milk  is  put  up  in  ac- 
cordance with  the  prescription.  This  milk  is  put  into 
small  bottles  containing  only  one  feed.  The  Walker 
Gordon  laboratories  are  in  operation  in  many  of  the  large 
cities  in  the  United  States,  and  do  a  large  volume  of 
business  along  this  line. 

Homogenized  Milk.1  —  This  class  of  milk  is  found  on 
the  markets  of  this  country  only  in  very  rare  instances, 
though  it  is  used  to  some  extent  in  European  countries. 

Homogenized  milk  seems  to  be  objected  to  in  this  coun- 

1  The  homogenizing  machine  and  the  use  of  homogenized  cream  for  ice- 
cream making  are  described  in  Chapter  XIX. 


MODIFIED    MILK  85 

try.  In  the  first  place,  there  is  a  wide  practice  of  using 
the  cream  from  the  top  of  the  bottle  for  coffee  or  other 
special  purposes.  This  cannot  be  done  when  homogen- 
ized milk  is  used,  because  there  is  no  apparent  cream 
on  homogenized  milk. 


FIG.  7.  —  The  Gaulin  homogenizer. 

The  consumer  commonly  judges  the  richness  of  milk 
by  the  amount  of  cream  that  can  be  seen  at  the  top  of  the 
bottle.  By  this  standard  homogenized  milk  does  not  show 
up  well. 

However,  in  all  cases  where  it  is  desirable  to  use  whole 


86  DAIRY  TECHNOLOGY 

milk  the  homogenized  milk  is  preferable  to  natural  milk, 
because  the  former  is  always  ready  to  use  without  mixing, 
and  the  cream  never  forms  in  hard  lumps  as  is  sometimes 
the  case  when  natural  milk  stands  for  a  long  period.  The 
fat  globules  of  homogenized  milk  are  very  minute,  which 
condition  makes  them  more  easily  digested.  It  is  also 
claimed  that  the  homogenization  process  destroys  many 
bacteria,  and  therefore  homogenized  milk  has  better 
keeping  properties.  This  latter,  however,  has  not  been 
thoroughly  investigated. 


CHAPTER  IX. 

[THE    VILLAGE    MILK    PLANT. 

THE  milk  supply  of  a  farm  community  is  not  so  vital 
a  problem  for  consideration  by  the  general  public,  because 
the  consumer,  as  a  rule,  is  his  own  producer.  The  con- 
sumer uses  the  quality  of  milk  that  he  produces,  and  if 
he  does  not  have  a  pure  and  sanitary  milk  for  use,  no  one 
but  himself  is  to  blame. 

In  the  small  city  or  village,  conditions  are  but  one  step 
more  complex  than  this.  The  consumer  is  supplied  with 
milk  by  his  neighbor,  who  generally  resides  just  outside 
of  the  village  limits.  The  city  milk  dealer  and  the  pro- 
ducer are,  as  a  rule,  one  and  the  same  person.  The  milk 
produced  in  the  morning,  together  with  that  of  the  pre- 
vious night,  is  delivered  to  the  consumer  the  same  morn- 
ing by  the  dairyman  who  produced  it.  This  milk  usually 
is  exposed  to  less  contamination,  and  is  kept  for  a  shorter 
time  before  delivery  than  the  ordinary  market  milk  of 
a  large  city.  But  from  a  sanitary  point  of  view  there  is 
wide  latitude  in  the  operation  of  small  city  milk  plants. 

Objectionable  Practices.  —  The  small  city  milk  plant, 
operating  on  but  a  small  scale,  cannot  afford  an  elaborate 
and  expensive  equipment.  In  many  places  hot  water 
and  steam  for  cleaning  purposes  are  available  only  in 
limited  supply,  which  results  in  less  thorough  cleaning 
of  bottles  and  utensils. 

A  number  of  practices  that  some  small  milk  dealers 
follow  should  be  condemned.  Among  these  are,  first, 

87 


88 


DAIRY  TECHNOLOGY 


the  selling  of  "  loose  milk,"  that  is,  dipping  out  from  a 
supply  can  the  amount  desired  by  the  purchaser,  and 
placing  it  in  a  pan  or  other  recep table;  second,  omitting 
to  wash  and  sterilize  returned  bottles  merely  because 


FIG.  8.  —  The  Bestov  milk-cooler. 

they   appear   to   be   clean  or  allowing   careless   cleaning 
in  the  milk  plant,  the  milk  bottles  when  refilled  without 
being  washed  may  be   the  means  of  spreading  disease; 
third,  filling  the  bottles  on  the  street. 
A  dairy  of  forty  or  more  cows  should  afford  a  well- 


THE   VILLAGE  MILK  PLANT 


equipped  milk  house;  and,  since  cleanliness  is  the  most 
important  consideration,  the  factors  of  prime  importance 
in  the  milk  house  are  sanitary  construction  and  a  small 
upright  boiler  to  furnish  an  abundant  supply  of  hot  water 
or  steam  for  cleansing  and  sterilizing. 

EQUIPMENT  OF  THE  PLANT. 

The  equipment  of  a  small  dairy  may  vary  between 
wide  limits,  depending  upon  size,  prosperity,  grade  of 
milk  produced,  and  the  individuality  of  the  owner. 

Cooling  the  Milk.  —  The  milk  may  be  cooled  by  setting 
the  cans  in  a  tank  of  water,  or  an  expensive  cooling  appara- 
tus may  be  used.     Between  these  extremes  are  numerous 
coolers   adaptable   to   all   conditions. 
Whatever   method  of  cooling  is  em- 
ployed, it  is  extremely  important  that 
the  milk  be  cooled  at  once  after  it  has 
been  drawn  from  the  cow. 

Bottling.  —  Bottles  may  be  filled  by 
pouring  from  a  pitcher  or  spouted  can, 
or  a  modern  bottle -filling  machine  may 
be  used.  Many  small  dairymen  use  a 
large  can  similar  to  a  small  weigh  can, 
but  having  one  or  two  small  faucets, 
under  which  bottles  are  placed  for  fil- 
ling. Superior  to  this,  but  more  costly, 
is  the  filler  with  the  automatic  cut-off 
valve,  that  insures  having  the  bottles 
filled  to  the  right  point  and  prevents 
overflowing.  When  bottles  are  filled 
in  this  way  there  is  no  milk  spilled  on  the  outside  of  the 
bottle.  The  bottle  is  filled  to  such  a  point  that  the  cap 
may  be  placed  upon  it  without  dipping  it  into  the  milk. 


FIG.  9.  —  Circular  disk 
milk  cooler. 


go 


DAIRY  TECHNOLOGY 


Capping  bottles  that  are  over  full  causes  the  excess  of  milk 
to  squirt  out  on  to  the  dairyman's  hands  and  to  drip  from 


FIG.  10.  —  Quaker  City  milk-filler. 

there  to  other  caps  and  into  other  bottles.     This  is  not 
sanitary. 

In  a  report  of  the  "  Association  for  Improvement  of  the 
Milk  Supply  of  New  York  City  "  is  given  the  bacterial 


THE  VILLAGE  MILK  PLANT 


content  of  milk  bottled  and  capped  by  hand  and  that  of 
milk  bottled  and  capped  by  machine.  The  average  of 
three  samples  of  each  class  of  milk  is  as  follows:  Bottled 
by  hand,  19,800  bacteria  per  cubic  centimeter;  bottled 
by  machine,  6266  bacteria  per  cubic  centimeter. 


FIG.  ii.  —  Davis  hand 
bottle  filler. 


FIG.  12.  —  Davis  hand 
bottle  capper. 


Capping  the  bottles  by  hand,  although  a  very  common 
practice,  is  not  so  sanitary  as  using  a  machine,  neither  is 
it  so  rapid.  Caps  for  machine  use  may  be  bought.  These 
are  packed  in  paper  tubes  direct  from  the  machine  which 
makes  the  caps.  These  tubes  are  sealed  so  that  the  caps 
are  not  exposed  to  dirt  and  dust.  Where  bulk  caps  are 
used,  they  may  be  loaded  into  the  metal  tubes  that  are 


92  DAIRY  TECHNOLOGY 

furnished  with  capping  machines  and  sterilized.  The 
simplest  machine  of  this  character  is  the  single  bottle 
capper,  though,  in  a  moderately  large  dairy,  the  combined 
filler  and  capper  is  found  more  economical  in  point  of 
time. 

Bottle  Washing.  —  Many  small  dairymen  object  to  the 
expenditure  necessary  to  secure  a  bottle-washing  outfit, 


FIG.  13.  —  Turbine  bottle  washer. 

but  the  time  saved  and  the  better  results  secured  by  a 
washer  will  soon  pay  for  one.  The  machine  best  adapted 
to  the  small  dairy  is  a  brush  revolved  by  a  steam  turbine 
or  by  a  water  motor,  combined  with  suitable  sinks  and 
rinsing  apparatus. 
The  small  dairy  that  is  equipped  with  a  steam  boiler  to 


THE   VILLAGE   MILK   PLANT  93 

supply  plenty  of  hot  water  for  washing  should  have  no 
difficulty  in  getting  the  bottles  and  cans  almost  sterile. 

A  sterile  oven  is  a  great  addition  to  a  dairy  room,  though 
a  rather  costly  one.  It  is  recommended  for  dairies  pro- 
ducing a  high  grade  of  sanitary  milk. 


CHAPTER  X. 

THE  CITY  MILK  PLANT. 

THE  large  milk  plant  of  a  great  city  requires  extensive 
equipment  and  a  large  building,  and  hence  calls  for  con- 
siderable capital  as  well  as  knowledge  of  the  dairy  business. 

The  milk  is  practically  all  received  by  rail,  so  that  it 
is  subjected  to  more  possibilities  of  contamination  than 
that  of  the  village  milk  dealer.  Generally  the  milk 
passes  through  the  hands  of  at  least  three  different  persons 
or  companies  —  the  farmer  or  producer,  the  transportation 
company  and  the  city  milk  company. 

Transportation.  —  Milk  may  be  transported  from  the 
place  of  production  to  the  market  by  steam  or  electric 
roads,  boats  or  wagons. 

In  practically  all  small  cities,  the  wagon  carries  most  of 
the  milk  from  the  farm  to  the  consumer.  And  even  in  some 
very  large  cities  this  mode  of  transportation  is  employed 
to  a  great  extent.  We  find  that  in  Washington,  D.  C.; 
Detroit,  Mich.;  San  Francisco,  Cal.,  and  St.  Louis,  Mo., 
about  half  of  the  milk  supply  of  the  city  comes  in  on  wagons ; 
while  in  Milwaukee,  Wis.;  Cincinnati,  Ohio,  and  New 
Orleans,  La.,  wagons  bring  about  three-fourths  of  the  milk. 
But  in  the  larger  cities,  such  as  New  York,  Chicago  and 
Philadelphia,  about  nine- tenths  of  the  milk  is  brought  in 
by  steam  and  electric  cars. 

Most  of  the  milk  that  is  shipped  less  than  100  miles  is 
carried  in  baggage  or  express  cars  attached  to  local  pas- 
senger trains.  But  for  greater  distances  special  refrigerator 

94 


THE   CITY  MILK  PLANT  95 

cars  are  commonly  used.  This  depends  upon  the  time 
of  year  and  the  weather  conditions.  For  milk  cars,  some 
roads  employ  a  modified  baggage  car  equipped  with  racks 
along  the  side  for  holding  ice.  A  better  milk  car  is  used 
by  one  of  the  roads  carrying  milk  to  New  York  City.  It 
is  a  refrigerator  car  with  a  capacity  of  325  eight-gallon 
cans,  having  an  ice  compartment  at  each  end,  so  that  milk 
may  be  kept  at  a  temperature  of  50°  F.  Every  day  the 
cars  are  scrubbed  and  thoroughly  cleaned. 

Another  road  has  refrigerator  milk  cars  with  asbestos- 
lined  walls,  sheet-steel  floors  and  regular  refrigerator  doors 
and  an  ice  capacity  of  500  pounds  at  each  end  of  the  car. 

The  careful  dairyman  delivers  his  well-cooled  milk  at 
the  station  a  short  time  before  the  arrival  of  the  car  or 
boat,  but  right  here  is  a  possibility  of  spoiling  milk.  Milk 
stations  are  often  merely  open  platforms  with  no  roof  or 
other  protection  for  the  cans  from  the  sun  and  heat  in  sum- 
mer. Milk  will  quickly  warm  to  the  danger  point  if  left  on 
such  a  platform.  And  as  delayed  trains  are  not  an  unusual 
thing,  the  souring  of  milk  while  in  the  hands  of  the  trans- 
portation company  is  not  an  infrequent  occurrence.  In 
the  older  dairy  districts  we  find  milk  stations  with  proper 
protection  for  the  milk  while  it  awaits  the  arrival  of  the 
train. 

Until  very  recent  years,  milk  was  brought  from  a  dis- 
tance by  steam  cars  or  by  boat,  but  the  electric  railway  is 
now  a  keen  competitor  for  the  hauling  of  milk  and  has 
some  advantages  over  the  other  methods  of  transportation. 
The  electric  lines  penetrate  the  rural  communities  to  a 
greater  extent  than  do  the  steam  roads,  so  that  the  farmer 
has  the  milk  station  closer  to  his  door.  The  electric  lines 
can  carry  their  loads  of  milk  to  the  center  of  the  city,  or 
to  the  milk  plant  itself,  instead  of  dumping  it  all  at  one 


96 


DAIRY   TECHNOLOGY 


great  depot,  located,  perhaps,  more  than  a  mile  from  the 
milk  plant,  as  is  done,  necessarily,  by  the  steam  road. 
Los  Angeles  has  satisfactorily  developed  the  milk  traffic  in 
this  way. 

Under  present  conditions,  in  most  cities,  milk  is  hauled 
by  dray  from  the  railway  station  to  the  city  milk  plant. 
This  extra  handling  and  labor  cannot  wholly  be  done  away 
with. 

The  Intake.  —  On  arrival  at  the  city  milk  plant  each 
can  must  be  inspected  by  an  experienced  man  with  a  keen 


FIG.  14.  —  A-F  gravity  conveyers  installed  in  Howell 
Condensed  Milk  and  Cream  Co.  plant. 

sense  of  smell.  Milk  containing  any  sour  or  other  un- 
desirable odor  is  not,  and  should  not  be,  accepted.  The 
inspection  of  milk  on  a  large  scale  is  done  almost  entirely 
by  the  sense  of  smell,  because  the  sense  of  taste  cannot  be 
relied  upon  after  several  hundred  cans  of  milk  have  been 
tasted  in  quick  succession. 

However,  there  are  other  tests  for  the  sanitary  condi- 
tion of  milk  which  are  very  useful  under  certain  conditions, 
but  are  not  being  extensively  used  in  this  country  at  the 
present  time,  (See  Chapter  XII.) 


THE   CITY  MILK   PLANT 


97 


The  cans,  when  empty,  may  be  turned  up  on  a  drip- 
saver,  which,  as  the  name  indicates,  saves  whatever  milk 
may  drip  out  from  the  cans.  Just  beyond  the  drip-saver 
is  the  can  washer.  The  cans  are  taken  from  the  drip-saver, 
washed,  steamed,  and  taken  out  by  another  door  to  the 
dray,  which  hauls  them  back  to  the  railway  station  to  be 
returned  to  the  shipper. 

Sanitary  Piping. —  Having  passed  the  inspector,  the  milk 
is  emptied  into  a  receiving  vat,  from  which  it  is  pumped 
into  a  storage  tank  that  feeds 
the  pasteurizer.  This  necessi- 
tates passing  the  milk  through 
considerable  piping  as  well  as 
a  pump.  Needless  to  say,  the 
pumps  should  be  of  the  sani- 
tary type,  so  that  they  may  be 
taken  apart  and  thoroughly 
cleaned  after  each  using.  The 
piping  must  be  the  so-called 
sanitary  piping,  being  tinned 
throughout,  having  a  perfectly 
smooth  interior,  and  in  short 
lengths  joined  by  couplings  eas- 
ily taken  apart  with  a  spanner 
wrench.  These  pipes  should  be 
washed  daily  by  rinsing  with 
cold  water,  then  pumping  hot 
washing  powder  solution  through  them  and  finally  rinsing 
with  plenty  of  boiling  hot  water. 

However,  they  should  be  taken  apart  and  thoroughly 
cleaned  with  a  brush  and  sterilized  at  least  once  each  week. 

Clarifying.  —  The  presence  of  dirt  or  sediment  of  any 
kind  in  milk  is  strenuously  objected  to  by  the  consumer. 


FIG.  15.  — The  Victor 
can  washer. 


98  DAIRY  TECHNOLOGY 

For  this  reason,  some  filter  and  clarify  the  milk.  Milk 
niters  have  not  given  much  satisfaction  and  are  not  used 
to  any  considerable  extent.  But  the  clarifying  of  milk 
by  centrifugal  force  is  being  adopted  to  a  large  extent  by 
city  milk  plants.  Some  of  them  use  an  ordinary  cream 
separator  and  run  the  cream  and  skim  milk  together.  At 
times  the  milk  is  standardized  to  the  desired  percentage  of 
fat. 

The  milk  clarifier  is  a  modification  of  the  cream  separa- 
tor, providing  a  greater  capacity  for  the  deposit  of  sedi- 
ment and  delivering  the  whole  milk  from  the  machine 
instead  of  separating  it.  Removing  dirt  from  milk  re- 
moves some  bacteria,  leucocytes,  etc.,  so  that  the  clarified 
milk  is  a  purer  and  cleaner  food. 

Pasteurization  and  Cooling.  —  The  large  city  milk  plant 
commonly  pasteurizes  the  milk,  and  for  this  purpose  an 
intermittent  pasteurizer  or  a  continuous  machine  with  a 
retarder  is  used,  usually  the  latter.  The  milk  is  heated  to 
from  140°  to  1 60°  F.  and  held  at  that  temperature  for  from 
15  to  30  minutes,  when  it  is  discharged  and  conducted  to 
the  cooler.  This  latter  is  very  commonly  a  vertical  coil 
of  pipes  over  which  the  milk  flows  in  very  thin  sheets, 
while  at  the  same  time  cold  water  or  brine  is  flowing  through 
the  interior  of  the  pipes,  entering  at  the  bottom  and  flow- 
ing out  at  the  top. 

The  pasteurization  of  milk,  to  be  successful  from  a 
commercial  standpoint,  must  be  so  carried  on  that  the 
keeping  qualities  of  the  milk  will  be  improved  without 
heating  to  such  an  extent  as  to  impart  a  cooked  flavor  or 
materially  to  injure  the  creaming  qualities  of  the  milk. 
It  is  a  well-known  fact  among  dairymen,  that  excessive 
heating  and  stirring  of  milk  breaks  the  clusters  of  fat 
globules  and  scatters  them  throughout  the  serum.  This 


THE    CITY   MILK   PLANT 


99 


FIG.  1 6.  —  The  De  Laval  centrifugal  clarifier. 


100  DAIRY  TECHNOLOGY 

makes  creaming  very  difficult,  because  the  small  globules 
are  unable  to  overcome  the  viscosity  of  the  milk  serum. 
In  unheated  milk  the  fat  globules  are  well  clustered,  and 
present  a  relatively  small  surface  as  compared  with  their 
volume.  The  creaming  of  milk  is  but  slightly  affected  by 
temperatures  up  to  150°  F.,  but  subjecting  it  to  a  tempera- 
ture of  160°  F.  for  20  minutes  retards  it  very  markedly. 

Pasteurizers.  —  The  pasteurization  of  milk  may  be 
accomplished  by  heating  at  a  low  temperature  for  a  long 
time  or  at  a  high  temperature  for  a  short  time.  One 
class  of  machines,  known  as  the  intermittent  or  batch 
pasteurizer,  is  so  operated  that  the  milk  may  be  heated 
at  any  temperature  for  any  desired  length  of  time.  These 
machines  are  commonly  vats  or  other  receptacles  in  which 
the  milk  is  heated  and  agitated  mechanically.  Cooling 
is  accomplished  by  passing  cold  water  through  the  agita- 
tor or  jacket  as  the  case  may  be.  These  machines  are 
very  efficient,  but  it  can  readily  be  seen  that  their  capacity 
is  limited,  and  hence  they  are  hardly  practicable  except 
in  a  small  business. 

The  other  class  of  pasteurizers  is  known  as  the  con- 
tinuous or  flask  machine,  because  there  is  a  continuous 
flow  of  milk  through  the  machine  and  it  is  heated  instan- 
taneously. The  milk  is  heated  to  a  high  temperature  and 
immediately  passed  on  to  the  cooler.  However,  it  has 
been  shown  by  experiment,  that  all  the  milk  is  not  heated 
to  the  same  temperature,  and  hence  some  of  it  will  not 
be  thoroughly  pasteurized  and  some  of  it  will  be  over- 
pasteurized. 

A  test1  of  one  of  the  commonly  used  machines  revealed 
the  fact  that  some  of  the  milk  passed  through  in  15  seconds, 
most  of  it  was  held  30  seconds  and  some  of  it  60  seconds. 
1  Russel  and  Hastings  —  Outlines  of  Dairy  Bacteriology. 


THE  CITY  MILK  PLANT  IOI 

It  is  evident  that  a  temperature  sufficiently  high  to  kill 
the  bacteria  in  the  milk  that  passed  through  in  15  seconds 
would  cause  undesirable  effects  on  the  milk  that  was 
exposed  for  60  seconds.  And  if  the  temperature  was 
regulated  on  the  basis  of  an  exposure  of  from  30  to  60 
seconds,  it  is  evident  that  the  milk  passing  through  in  15 
seconds  would  be  inefficiently  pasteurized. 

The  necessity  of  a  continuous  pasteurizer  and  the  faults 
of  the  first  machines  led  to  the  adoption  of  "  holding  " 
devices  or  "  retarders.  "  In  such  machines  the  milk 
is  passed  through  a  continuous  pasteurizer  into  a  holding 
tank  in  which  it  is  kept  at  the  desired  temperature  for 
the  desired  length  of  time,  then  passed  on  to  the  cooler. 
Thus  the  good  qualities  of  the  two  classes  of  pasteurizers 
are  combined  in  one.  These  machines  may  be  equipped 
with  a  thermo-regulator  which  automatically  regulates 
the  flow  of  steam  to  the  pasteurizer  and  insures  a  uniform 
heating  of  the  milk.  In  connection  with  this  a  recording 
device  is  commonly  used,  GO  that  the  slight  variations  in 
temperature  are  recorded. 

Pasteurization  applied  to  fresh,  clean  milk,  and  to  old, 
impure  milk  may  destroy  99  per  cent  of  the  bacteria  in 
both  cases.  Now  it  is  quite  evident  that  the  clean  milk 
before  and  after  pasteurization  would  contain  by  far  the 
smaller  number  of  bacteria,  and  hence  would  have  the 
better  keeping  qualities  and  be  more  healthful. 

Immediate  cooling  to  about  40°  F.  subsequent  to  heat- 
ing is  necessary  for  successful  pasteurization;  also  all 
contamination  after  pasteurization  must  be  guarded 
against. 

Pasteurization  in  the  Bottle.  —  Another  method  of 
pasteurizing  milk  that  has  been  introduced  recently  is 
pasteurization  in  the  bottles.  This  method  necessitates 


102 


DAIRY  TECHNOLOGY 


the  use  of  a  perfectly  tight  cap,  one  that  will  withstand 
the  action  of  hot  water  and  steam.  Breweries  have  used 
such  a  method  of  pasteurizing  their  bottled  beer  for  a 
number  of  years,  while  the  dairy  industry  has  but  recently 
adapted  it  to  bottled  milk. 

One  of  the  objections  to  the  commercially  pasteurized 
milk  of  to-day  is  that,  although  the  pasteurization  may 
have  been  efficient,  contamination  during  the  cooling, 


FIG.  17.  —  A  type  of  beer-pasteurizing  machine  adaptable  to  the  pasteuri- 
zation of  milk  in  bottles.     (Circular  184,  U.  S.  Dairy  Division.) 

bottling  and  capping  processes  is  inevitable,  and  this 
contamination  may  be  of  a  very  serious  nature.  Pas- 
teurization in  the  bottle  prevents  such  contamination 
and  insures  a  safer  product. 

Pasteurization  of  bottled  milk  is  carried  on  to  a  limited 
extent  in  steam  sterilizers,  but  a  more  efficient  process 
is  by  the  use  of  water.  In  the  brewery  there  are  two 
general  classes  of  these  pasteurizers.  In  one  type  the 


THE   CITY  MILK   PLANT 


103 


bottles  are  placed  in  baskets,  which  are  carried  on  an 
endless  chain  into  tanks  of  water  having  different  tem- 
peratures. In  this  way  the  bottles  are  passed  through 
lukewarm  water,  then  through  warmer  and  warmer  water, 
until  they  reach  the  pasteurizing  temperature.  They  re- 
main at  this  temperature  for  20  minutes  or  any  desired 
time;  then  they  pass  through  a  series  of  cooling  tanks, 
each  successive  tank  containing  cooler  water  than  the 
previous  one. 

In  the  other  type  of  machine,  the  bottles  are  placed 
in  trays  on  a  large  wheel  revolving  horizontally,  where 
they  receive  a  heavy  shower  bath  of  water.  As  the  wheel 
revolves  the  bottles  pass  through  water  of  different  tem- 
peratures just  as  in  the  above-described  system,  so  that 
pasteurization  and  cooling  are  accomplished  by  a  con- 
tinuous process. 

Mr.  Bixby1  of  Boston  compared  pasteurization  in  a 
machine  with  pasteurization  in  bottles  and  secured  the 
following  results: 

NUMBER  OF  BACTERIA  IN  ONE  CUBIC  CENTIMETER 
OF  MILK. 


Raw. 

Pasteurized  in 
machine. 

Pasteurized  in 
bottles. 

2,OOO,OOO 

99,000 

30,000 

2,OOO,OOO 

102,000 

34,000 

6,300,000 

42,000 

6,600 

1,960,000 

70,000 

1,200 

6,2OO,OOO 

65,000 

4,000 

2,100,000 

65,000 

8,100 

In   both   these   methods   of   pasteurization,    the   same 
degree  of  heat  and  same  time  of  exposure  were  employed. 

1  Medical  Record.  —  July  15,  1911. 


104 


DAIRY  TECHNOLOGY 


It  is  very  evident  from  these  figures  that  heating  in  the 
bottles  gives  by  far  the  better  results. 

In  a  similar  experiment  carried  on  by  Dr.  Charles  E. 
North,  New  York,  pasteurization  in  bottles  reduced  the 
bacterial  content  of  the  milk  from  about  500,000  to  500 

.  ,  . 


FIG.  18.  —  The  Davis  bottle  filler  and  capper, 

per   cubic   centimeter.     This   was   accomplished   without 
affecting  the  flavor  or  creaming  of  the  milk. 

Bottling.  —  After  pasteurization  and  cooling,  the  milk 
may  be  conducted  to  a  storage  tank  of  glass-enameled 
iron  located  in  a  cold  room.  It  is  now  ready  to  be  bottled. 
For  filling  and  capping  bottles,  on  a  large  scale,  an  auto- 
matic, power-driven  machine  is  commonly  used.  It 
may  be  run  by  an  electric  motor  so  that  a  movement  of 
a  lever  causes  a  case  of  bottles  to  be  filled  and  capped. 
The  labor  required  to  operate  such  a  machine  consists  of 
one  man  to  feed  in  the  cases  of  empty  bottles,  and  one  man 
to  take  the  filled  bottles  from  the  machine.  If  gravity 
conveyers  are  used,  the  man  who  takes  the  cases  of  filled 


THE   CITY  MILK  PLANT 


105 


bottles  from  the  filler  may  place  them  on  a  conveyer 
which  conducts  them  to  a  cold  room  for  storage  until 
called  for  by  the  delivery  wagon. 

Delivering.  —  Cases  of  filled  bottles  are  usually  hauled 
to  the  loading  platform  on  hand  trucks,  and  frequently 
have  to  be  taken  to  the  floor  above  on  an  elevator.  A 
system  more  economical,  in  the  use  of  time  and  labor,  is 


FIG.  19.  —  Davis  Standard  12  bottle  filler. 

that  of  the  gravity  conveyer  and  automatic  elevator,  by 
means  of  which  filled  cases  may  be  taken  to  the  platform 
as  fast  as  they  can  be  loaded  into  the  wagons. 

Cases  of  empty  bottles  are  readily  conveyed  to  the 
washing  room  by  the  same  method. 

Bottle  Washing.  —  The  simplest  method  of  washing 
bottles  is  by  means  of  a  revolving  brush  as  described  under 
"The  Village  Milk  Plant,"  But  this  is  not  economical 


io6 


DAIRY  TECHNOLOGY 


when  a  great  number  of  bottles  must  be  washed  and  ster- 
ilized each  day.  The  modern  bottle-washer  handles  the 
glassware  in  cases,  taking  them  in  at  one  end,  just  as  they 
come  from  the  wagons,  and  delivering  them  at  the  other 
end  perfectly  clean  and  sterilized. 

In  general  there  are  two  kinds  of  bottle  washers:  that 
in  which  brushes  are  used,  and  that  in  which  jets  of  water 
are  relied  upon  to  do  all  the  cleaning. 


FIG.  20.  —  A-F  gravity  conveyers  in  Gridley  Dairy  Co.  plant, 
carrying  bottles  from  wagons  to  basement. 

The  automatic  brush  bottle  washer  soaks,  washes  with 
water  under  pressure  and  with  brushes,  and  rinses  and 
sterilizes  the  bottles.  Sanitary  cases  may  be  used  and  the 
bottles  kept  in  these  cases  during  washing,  rilling,  capping, 
and  even  on  the  wagon,  so  that  separate  handling  of  bottles 
is  unnecessary.  This  not  only  saves  a  great  deal  of  time, 
but  also  reduces  the  breakage  to  a  minimum.  In  the 
operation  of  the  machine,  the  cases  of  bottles  are  passed 
through  the  washer  by  means  of  a  carrier,  which  operates 
automatically,  stopping  a  sufficient  length  of  time  for 


THE   CITY  MILK  PLANT 


107 


io8 


DAIRY  TECHNOLOGY 


the  various  operations  and  discharging  the  bottles  clean, 
practically  sterile  and  hot.    They  dry  quickly  and  assume 


FIG.  22.  —  Steam  chamber,  showing  method  of  steaming  bottks. 
(Circular  184,  Dairy  Division,  TL  S.  Dept.  of  Agr.) 

a  good  clear  luster.    The  washing  process  requires  about 
five  minutes. 

The  high-pressure  bottle  washer  operates  similarly  to 
the  brush  washer,  except  that  in  the  former  no  brushes  are 
used.  The  work  of  the  brush  is  accomplished  by  jets  of 
water  under  high  pressure.  Large  quantities  of  water 


THE  CITY  MILK  PLANT  ICX) 

are  pumped  over  and  over  again  with  great  force  against 
the  bottles,  both  inside  and  outside.  The  water  in  the 
tanks  is  renewed  automatically  and  continuously,  a  small 
stream  of  water  coming  in  and  a  small  stream  of  impure 
water  running  out. 

The  Milk  Bottle.  —  The  only  style  of  milk  bottle  used 
to  any  extent  at  the  present  time  is  that  made  of  glass. 
The  advantages  of  a  glass  bottle  are  as  follows: 

1.  It  is  easily  cleaned  and  sterilized. 

2.  The  consumer  can  easily  detect  the  presence  of 

dirt  of  any  kind  in  the  bottle  or  the  milk. 

3.  It  cannot  itself  impart  any  flavor  to  the  milk, 

and  forms  a  perfectly  tight  package  to  keep  out  all 
dirt,  flavors,  etc. 

4.  It  cannot  corrode  nor  become  unsanitary  in  any 

way,  however  old  it  may  become. 

The  disadvantages  of  a  glass  bottle  are: 

1.  It  is  fragile. 

2.  It  is  costly. 

3.  It  is  heavy. 

4.  Unless  sterilized  before  being  filled  it  may  become 

a  carrier  of  disease. 

Because  of  these  disadvantages,  numerous  attempts 
have  been  made  to  introduce  a  single-service  container 
made  of  paraffined  paper.  This  seems  to  be  the  only 
alternative  to  glass,  all  metals  being  out  of  the  question. 
But  the  consumer  cannot  see  the  thickness  of  the  layer 
of  cream  on  the  top,  he  cannot  tell  whether  the  milk  in 
the  paper  container  is  clean  or  not,  and  the  package  is 
not  so  pleasing  to  the  eye.  These  are  the  chief  reasons 
for  the  failure  of  the  single-service  container  to  be  gen- 
erally adopted. 


no 


DAIRY  TECHNOLOGY 


The  Bottle  Cap.  —  Bottles  of  ordinary  market  milk 
are  commonly  capped  with  a  pulp  cap  that  fits  into  the 
countersink  mouth  of  the  bottle.  This  leaves  the  lip 
of  the  bottle  exposed  to  the  accumulation  of  dirt  and 


FIG.  23.  —  This  shows  a  type  of  sanitary  bottle  cap,  and  method  of 
removing  same. 

bacteria.  When  milk  is  poured  from  such  a  bottle  it 
flows  over  and  carries  with  it  whatever  contamination 
may  be  there. 

Producers  of  certified  milk  have  adopted  various  de- 
vices to  protect  the  lip  of  the  bottle,     Many  of  them  use 


THE   CITY  MILK  PLANT 


III 


the  ordinary  cap  with  a  large  hoodlike  paper  cap  covering 
the  entire  top  of  the  bottle.  Others  use  a  cap  that  fits 
tightly  over  the  opening  of  the  bottle,  insuring  a  tight 
seal  and  protecting  the  lip  at  the  same  time. 

Another  style  of  cap  being  introduced  is  that  similar 
to  the  cap  used  on  pop  and 
beer  bottles,  a  metal  cap  lined 
with  a  fiber  disk.  These  caps 
can  be  used  only  on  bottles 
made  for  this  purpose.  They 
are  placed  upon  the  bottle  by 
a  machine  that  forces  the  cor- 
rugated skirt  of  the  metal 
crown  under  the  locking  ring 
of  the  bottle,  thus  forming  a 
hermetically  tight  seal,  remov- 
able only  by  means  of  a  bottle 
opener.  This  crown  effectu- 
ally protects  the  mouth  of  the 
bottle.  Machines  are  on  the 
market  for  automatically  filling 
and  capping  bottles  of  this 
kind.  With  this  system,  milk 
can  be  pasteurized  in  the  bottles  and  thus  avoid  possible 
contamination  during  cooling  and  filling  of  bottles. 

Business  Principles.  —  The  business  of  handling  a 
large  quantity  of  a  perishable  product  demands  close 
watchfulness  on  the  part  of  the  managers  to  avoid  losses. 
The  daily  income  and  output  of  milk  must  be  the  same, 
as  near  as  is  possible  to  have  it.  Because  of  the  per- 
ishable quality  of  the  product,  and  because  of  the  large 
quantity  that  must  be  handled  in  a  short  time  each  day, 
experienced  help  and  efficient  machinery  are  necessary. 


FIG.  24.  —  Another  type  of  a 
sanitary  bottle  cap. 


112 


DAIRY  TECHNOLOGY 


FIG.  25.  — The  foot  milk  bottle 
crowning  machine. 


The  best  of  both,  though 
high  priced  to  start  with, 
are  cheaper  in  the  long 
run.  The  retail  milk 
business  is  one  in  which 
the  sales  are  all  for  small 
amounts,  hence  the  profit 
on  each  sale  is  very  small. 
Success,  therefore,  de- 
pends upon  a  close  atten- 
tion to  minute  details. 

One  of  the  problems 
of  greatest  importance  is 
how  to  keep  a  close  check 
on  the  deliverymen.  The 
manager  usually  does 
not  come  in  direct  con- 
tact with  the  custom- 
ers; minor  employees  out 
through  the  city,  away 
from  the  supervision  of 
the  employer,  have  to  be 
trusted  entirely  with  the 
dealings  with  customers, 
the  handling  of  the  en- 
tire finished  product,  the 
cash  and  the  return  of 
empty  bottles. 

The  following  system 
of  checking  the  drivers 
is  being  used  successfully 
in  several  large  plants: 
When  the  driver  goes 


THE   CITY  MILK  PLANT 


out  in  the  morning  he  is  charged  with  the  number  of  bottles 
of  milk,  the  number  of  tickets  or  sheets  of  tickets  and  the 
cash  he  has  in  his  possession.  When  he  returns  from  the 
trip,  he  is  again  checked  up  and  must  have  a  used  ticket 
or  cash  to  account  for  every  bottle  of  milk  disposed  of. 
He  should  also  have  an  empty  bottle  for  each  full  one 
sold.  This  latter  is  rather  difficult,  unless  there  is  some 


FIG.  26.  —  A  motor  truck  specially  equipped  for  handling  dairy  products. 
In  the  service  of  the  Sheffield  farms,  N.  Y. 

incentive  for  the  driver  to  return  the  empties.  Probably 
the  best  way  to  prevent  the  loss  of  empty  bottles  is  to 
scale  the  wage  on  a  basis  of  the  number  of  empty  bottles 
returned.  For  instance,  some  companies  pay  their  drivers 
one  dollar  per  day  and  one  cent  for  each  empty  bottle 
returned.  Under  this  system  the  driver  is  pretty  sure  to 
induce  his  customers  to  have  an  empty  bottle  ready  for 
him  each  day. 


CHAPTER    XI. 

STANDARDIZATION  OF  MILK  AND  CREAM. 

To  standardize  milk  is  to  bring  the  butter-fat  content 
to  a  given  per  cent  regardless  of  the  quality  of  the  milk 
produced  by  the  cow.  Standardizing  milk  usually  is 
done  by  the  producer,  because  he  cannot  afford  to  pro- 
duce, say,  5-per-cent  milk,  and  sell  it  at  the  same  price 
that  4-per-cent  milk  sells  for.  Neither  can  the  consumer 
afford  to  pay  for  5-per-cent  milk  when  only  4-per-cent  milk 
is  delivered,  so  that  some  milk  companies  now  guarantee 
their  milk  to  contain  a  certain  per  cent  of  fat  in  return  for 
a  stated  price  to  be  paid  by  the  Consumer. 

Standardization  of  milk  may  be  accomplished  in  the 
following  cases: 

I.  Where  the  per  cent  of  fat  is  to  be  reduced  by  the 
addition  of  skim  milk. 

(a)  Quantity  of  standardized  milk  not  specified. 

(b)  Quantity  of  standardized  milk  specified. 

II.  Where  the  per  cent  of  fat  is  to  be  increased  by  the 
extraction  of  skim  milk. 

(a)  Quantity  of  standardized  milk  not  specified. 
(6)  Quantity  of  standardized  milk  specified. 

III.  Where  the  per  cent  of  fat  is  to  be  reduced  by  the 
addition  of  milk  having  a  lower  fat  content. 

(a)  Quantity  of  standardized  milk  not  specified. 
(6)  Quantity  of  standardized  milk  specified. 

114 


STANDARDIZATION  OF  MILK  AND   CREAM 


IV.  Where  the  per  cent  of  fat  is  to  be  increased  by  the 
addition  of  milk  having  a  higher  fat  content. 

(a)  Quantity  of  standardized  milk  not  specified. 

(b)  Quantity  of  standardized  milk  specified. 

Formulas  and  Examples : 

I.  (a)  To  obtain  milk  containing  3.2  per  cent  of  fat, 
from  milk  containing  4  per  cent  of  fat  and  skim  milk. 

Draw  a  square.  At  the  two  left-hand  corners  write  the 
numbers  which  represent  the  per  cent  of  fat  in  the  two 
liquids  which  are  to  be  mixed.  In  the  center  of  the  square 


x 


3.2  parts  of  4#  milk 


y 

"^8  parts  of  skimmilk 
FlG.  27.  4.0  parts  of  3.2#  milk 

write  the  number  representing  the  percentage  of  fat  re- 
quired. Then  subtract  the  two  numbers  standing  in 
line  across  the  diagonals  of  the  square  and  place  the  differ- 
ence at  the  remaining  two  corners  in  such  a  way  as  to 
have  the  difference  stand  in  line  with  the  minuend  and 
subtrahend.  These  last  two  numbers  will  indicate  the 
proportions  to  be  taken  of  the  fluids  whose  percentages 
stand  in  the  same  horizontal  line. 

Since  3.2  :  0.8  :  :  4  :  i  then  we  require  4  parts  of  4  per 
cent  milk  and  i  part  of  skim  milk  to  produce  5  parts  of 
milk  containing  3.2  per  cent  of  fat. 


Il6  DAIRY  TECHNOLOGY 

The  following  formula  may  be  used  when  the  percentage 
is  a  convenient  number  to  work  with:  Divide  the  per 
cent  of  fat  in  the  milk  that  is  desired  by  the  per  cent  of 
fat  in  the  milk  on  hand.  The  result  will  be  the  per  cent 
of  the-milk  on  hand  to  be  taken.  The  remaining  per  cent 
of  milk  will  be  the  skim  milk  to  be  used. 

The  correctness  of  the  graphical  illustration,  Fig.  27, 
may  be  proven  as  follows: 

Let  p  be  the  per  cent  of  fat  in  the  cream  of  the  richer  of 
the  two  milks. 

Let  q  be  the  per  cent  of  fat  in  the  milk  of  the  poorer  of 
the  two  milks. 
Let  r  be  the  per  cent  of  fat  required, 

x  be  the  quantity  of  richer  milk  required, 
y  be  the  quantity  of  thinner  milk  required. 

Then  px  is  the  fat  in  the  richer  milk  for  new  mixture, 
qy  is  the  fat  in  the  poorer  milk  of  new  mixture, 

(x  +  y)  is  quantity  of  new  mixture, 
r  (x  +  y)  is  the  fat  in  new  mixture, 
px  H-  qy  is  the  fat  in  new  mixture. 
Therefore,  px  +  qy  =  r(x  +  y). 
Solving,  px  +  qy=rx  +  ry. 

px  —  rx  =  ry  —  qy. 
x(p-r)  =  y(r-q). 

Then  dividing  both  sides  of  the  equation  by  y  (p  —  r) 
we  have 

x  _  r  —  q 
y~  p-r 

Substituting  with  figures  from  the  above  example  we  have 

&*;*£». 

8   "    8 


STANDARDIZATION  OF  MILK  AND   CREAM         117 

In  the  above  example  we  would  have  3.2  -r-  4  =  0.80. 
Hence  80  per  cent  of  4-per-cent  milk  and  (100  —  80  =  20) 
20  per  cent  of  skim  milk  will  produce  milk  containing  3.2 
per  cent  of  fat. 

I.  (b)  To  obtain  100  pounds  of  milk  containing  3.2  per 
cent  of  fat  from  milk  containing  4  per  cent  of  fat,  and  skim 
milk. 

Determine  the  number  of  pounds  of  fat  required.  Divide 
this  number  by  the  per  cent  of  fat  in  the  known  milk.  This 
will  give  the  pounds  of  known  milk  required. 

i oo  X  3.2  per  cent  =  3.2  which  is  the  pounds  of  fat  in 
100  pounds  of  3.2  per  cent  milk. 

3.2  -r-  4  =  0.80  or  80  per  cent,  which  is  the  proportion 
of  4-per-cent  milk  required  to  make  3.2-per-cent  milk. 

80  per  cent  of  100  pounds  =  80  pounds,  the  required 
pounds  of  4-per-cent  milk. 

100  —  80  =  20,  the  required  pounds  of  skim  milk. 

II.  (a)  To  obtain  milk  containing  4  per  cent  of  fat  from 
milk  containing  3.2  per  cent  of  fat  by  the  extraction  of  skim 
milk. 

— —  =  pounds  of  skim  milk  to  be  removed. 
s 

When    r  =  the  per  cent  of  fat  in  the  known  milk, 

5  =  the  per  cent  of  fat  in  the  standardized  milk, 
x  =  the  pounds  of  known  milk. 

By  substituting  in  the  formula 

— ^-^  =  0.2  x  =  pounds  of  skim  milk  to  be  removed. 

4 

By  removing  from  a  given  quantity  of  3.2  per  cent 
milk,  skim  milk  equal  to  0.2  of  the  weight  of  that  milk, 
4-per-cent  milk  will  be  obtained. 


n8 


DAIRY  TECHNOLOGY 


II.  (b)  To  obtain    100  pounds  of  milk   containing  4 
per  cent  of  fat  from  milk  containing  3.2  per  cent  of  fat  by 
the  extraction  of  skim  milk. 

Find  pounds  of  fat  required.  Then  divide  the  desired 
pounds  of  fat  by  the  per  cent  of  fat  in  the  known  milk  and 
multiply  the  quotient  by  100.  The  difference  between 
this  product  and  the  pounds  of  standardized  milk  is  the 
pounds  of  skim  milk  to  be  extracted. 

(4  -r-  3.2)  X  ioo  =125,  which  is  the  pounds  of  3.2-per- 
cent milk  required  to  make  ioo  pounds  of  4-per-cent  milk. 

125  —  ioo  =  25  which  is  the  pounds  of  skim  milk  to 
be  extracted. 

III.  (a)  To  obtain  milk  containing  3.5  per  cent  of  fat 


3.2 


3  parts  of  4#  milk 


FIG.  28. 


X5  parts  of  3.2^  milk 
.8  parts  of  3.5^  milk 


from  milk  containing  4  per  cent  of  fat,  by  the  addition  of 
milk  containing  3.2  per  cent  of  fat. 

Same  method  as  is  used  in  solving  I.  (a). 

III.  (b)  To  obtain  160  pounds  of  milk  containing  3.5 
per  cent  of  fat  from  milk  containing  4  per  cent  of  fat,  by  the 
addition  of  milk  containing  3.2  per  cent  of  fat. 

Same  formula  as  is  used  in  solving  I.  (a). 

0.8  :  1 60  :  :  0.3  :  60.  Hence  60  pounds  of  4-per-cent 
milk  are  required. 


STANDARDIZATION  OF  MILK  AND   CREAM  119 

0.8  :  160  :  :  0.5  :  100.  Hence  100  pounds  of  3.2-per- 
cent milk  are  required. 

IV.  (a)  To  obtain  milk  containing  3.5  per  cent  fat 
from  milk  containing  3.2  per  cent  of  fat  by  the  addition  of 
milk  containing  4-per-cent  milk. 

Same  formula  as  used  in  solving  I.  (a). 

IV.  (&)  To  obtain  160  pounds  of  milk  containing  3.5 
per  cent  of  fat  from  milk  containing  3.2  per  cent  of  fat  by 
the  addition  of  milk  containing  4  per  cent  of  fat. 

Same  problem  as  in  III.  (b). 

Standardization  of  Cream.  —  The  standardization  of 
cream  is  of  still  greater  importance  than  the  standardiza- 
tion of  milk,  because  the  variation  of  the  percentage  of 
fat  in  cream  is  relatively  greater  than  that  of  the  milk. 
The  fat  content  of  cream  under  normal  conditions  varies 
'between  10  per  cent  and  50  per  cent,  while  that  of  milk 
seldom  varies  over  2  per  cent  or  3  per  cent. 

When  a  certain  volume  of  cream  is  being  sold,  a  com- 
paratively larger  amount  of  butter  fat  is  disposed  of  than 
when  the  same  volume  of  milk  is  sold.  As  it  is  the  butter 
fat  which  is  the  most  valuable  part  of  cream  and  milk, 
it  is  a  good  plan  to  regulate  the  price  of  cream  according 
to  (i)  the  percentage  of  fat  in  the  cream,  (2)  the  current 
price  of  the  butter  or  butter  fat. 

Even  when  the  same  separator  is  being  used  daily,  the 
percentage  of  fat  in  the  cream  is  likely  to  vary  as  much  as 
5  per  cent.  This  variation,  if  cream  is  not  standardized, 
.may  cause  a  considerable  loss  to  either  consumer  or  pro- 
ducer. For  instance,  suppose  25  gallons  of  cream  should 
contain  20  per  cent  of  fat,  and  it  was  unknowingly  increased 
to  25  per  cent,  there  would  than  be  5  per  cent  more  than 
the  standard  required.  If  this  cream  were  sold  at  80  cents 
a  gallon,  the  price  per  pound  of  fat  in  the  first  case  would 


120  .    DAIRY  TECHNOLOGY 

be  50  cents.  If  the  cream  tests  25  per  cent  instead  of  20 
per  cent,  0.4  of  a  pound  of  fat  too  much  is  given  in  each 
gallon  of  cream.  In  25  gallons  of  cream  10  pounds  too 
much  would  be  given.  This,  at  50  cents  per  pound,  would 
make  a  loss  of  $5.00  to  the  producer  from  the  sale  of 
25  gallons  alone.  Such  a  loss  would  affect  the  profit 
directly. 

The  principal  difference  between  milk  and  cream  is 
that  cream  contains  a  larger  per  cent  of  fat  than  does 
milk.  For  this  reason,  the  same  methods  which  apply  to 
the  standardization  of  milk  will  also  apply  to  the  standard- 
ization of  cream. 

When  the  cost  of  butter  fat  is  to  be  taken  into  consider- 
ation, then  a  separate  process  must  be  applied.  If  it  is 
desired  to  find  the  price  of  butter  fat  when  so  much  is 
obtained  per  gallon,  then  first  multiply  the  pounds  of 
cream  per  gallon  by  the  per  cent  of  butter  fat  in  the  cream. 
The  product  will  equal  the  pounds  of  fat  per  gallon  of 
cream.  Then  divide  the  price  per  gallon  of  cream  by  the 
number  of  pounds  of  butter  fat.  The  quotient  will  be 
the  price  per  pound  of  butter  fat. 

Example.  What  is  the  price  per  pound  of  butter  fat 
when  cream  containing  20  per  cent  of  fat  sells  for  50  cents 
per  gallon? 

A  gallon  of  cream  weighs  about  8  pounds. 

8  pounds  X  0.20  =  1.60  pounds  of  fat  in  a  gallon  of 
cream. 

.50  divided  by  1.6  equals  $0.31,  the  price  of  a  pound  of 
butter  fat. 

If  it  is  desired  to  calculate  the  price  of  a  gallon  of  cream 
when  butter  fat  is  worth  a  certain  price,  then  multiply  the 
pounds  of  cream  per  gallon  by  the  per  cent  of  fat  in  the 
cream.  The  product  will  represent  the  number  of  pounds 


STANDARDIZATION  OF  MILK  AND   CREAM          121 

of  butter  fat  in  one  gallon  of  cream.  Multiply  this  prod- 
uct by  the  price  per  pound  of  butter  fat  desired.  The 
product  will  represent  the  price  per  gallon  of  cream. 

Example.  At  30  cents  per  pound  of  fat  what  would 
be  the  price  of  a  gallon  of  cream  containing  25  per  cent 
of  butter  fat? 

8  X  0.25  =  2  pounds  of  butter  fat. 

2  X  30  cents  =  60  cents,  the  price  per  gallon  of  cream 
testing  25  per  cent  of  fat. 

In  case  it  is  desired  to  make  use  of  butter  prices,  it  is 
essential  to  increase  the  fat  by  the  average  overrun. 

If  it  is  desired  to  find  the  equivalent  price  per  gallon 
of  cream  containing  different  per  cents  of  butter  fat,  the 
following  method  is  the  quickest. 

Example.  If  cream  containing  20  per  cent  of  fat  is 
worth  60  cents  per  gallon,  what  is  cream  worth  containing 
25  per  cent  of  fat? 

0.20  :  0.25  :  :  0.60  :  x. 
60  X  0.25  =  15. 

15  divided  by  20  equals  0.75,  the  equivalent  price  of  25- 
per-cent  cream. 

In  some  instances,  cream  is  sold  for  so  much  per  quart 
for  each  per  cent  of  fat  it  contains.  The  usual  price  when 
sold  in  this  way  is  one  cent  per  quart  for  each  per  cent  of 
fat  it  contains.  For  instance,  if  the  cream  contains  25 
per  cent  of  fat,  then  the  price  of  it  would  be  25  cents  per 
quart.  If  it  contained  35  per  cent  of  fat,  it  would  be 
worth  35  cents  per  quart,  etc.  In  case  the  quality  of 
cream  varies,  this  is  a  fairly  good  basis  upon  which  to  fix 
the  price  of  cream. 

In  all  instances,  when  milk  or  cream  is  being  standard- 
ized, care  should  be  taken  not  to  mix  old  cream  with  fresh 
milk,  or  vice  versa.  Old  cream  and  fresh  milk,  in  the  first 


122  DAIRY  TECHNOLOGY 

place,  do  not  mix  as  well  as  when  both  are  fresh.  Lumps 
of  cream  are  likely  to  remain,  even  though  it  may  seem  as 
if  the  two  had  been  mixed  well.  Thus  an  unattractive 
appearance  is  caused.  Secondly,  the  older  cream  or  milk,  as 
a  rule,  contains  a  large  number  of  bacteria,  and  in  some 
instances  undesirable  ones.  These  when  mixed  with  the 
good  milk  will  cause  the  keeping  property  of  the  whole  to 
be  lessened,  and  in  some  instances  cause  the  whole  mixture 
to  assume  abnormal  qualities. 


CHAPTER  XII. 
SANITARY  EXAMINATION  OF  MILK. 

SEVERAL  cities  have  adopted  bacterial  standards  for  milk. 
Rochester,  N.  Y.,  requires  that  the  bacterial  content  of 
their  city  milk  be  kept  below  100,000  per  cubic  centimeter. 
Boston  permits  500,000  per  cubic  centimeter,  and  other 
cities  have  different  requirements  for  different  grades  of 
milk. 

The  number  of  bacteria  in  milk  cannot  be  determined 
until  24  to  48  hours  after  the  sample  was  taken,  by  which 
time  the  milk  has  been  consumed.  A  milk  dealer  demands 
a  quicker  test  for  the  quality  of  the  milk.  Since  the  age 
of  milk  is  indicated  somewhat  by  the  degree  of  acidity, 
the  acid  test  is  used  to  some  extent  to  determine  the 
quality  of  the  milk. 

Acidity  Test.  —  The  simplest  method  of  determining 
roughly  the  acidity  of  milk  is  by  the  use  of  Farrington's 
Alkaline  Tablets,  using  a  solution  made  of  one  tablet  to  one 
ounce  of  hot  water.  Using  the  same  unit  for  the  measure- 
ment of  both,  the  milk  and  the  alkaline  solution,  one  volume 
of  alkaline  solution  added  to  one  volume  of  milk  will  neu- 
tralize acid  equivalent  to  one- tenth  of  one  per  cent.  If  the 
addition  of  two  volumes  of  alkaline  solution  to  one  of  cream 
does  not  neutralize  all  the  acid  (turn  the  milk  pink),  then 
that  milk  contains  more  than  two-tenths  of  one  per  cent 
acid,  and  is  not  a  first-grade  product. 

123 


I24 


DAIRY  TECHNOLOGY 


Sediment  Test.  —  The  cleanliness  of  milk  is  indicated 
somewhat  by  the  amount  of  dirt  or  sediment  it  contains. 
There  is  no  way  of  extracting  all  the  dirt  that  may  have 
fallen  into  the  milk  during  or  subsequent  to  milking,  be- 
cause nearly  one-half  of  ordinary  barn  dirt  is  soluble; 
hence  the  presence  of  a  small  quantity  of  visible  dirt  is 
usually  an  indication  that  a  greater  quantity  is  present 


FIG.  29.  —  The  Wisconsin  milk  sediment  tester. 

in  the  milk.  The  cleanliness  of  milk  may  be  roughly 
ascertained  by  centrifuging  a  sample,  or  by  filtering  a 
certain  volume  through  absorbent  cotton  and  noting  the 
amount  of  discoloration  and  filth  deposit  on  the  filter. 
Tests  for  this  latter  purpose  are  manufactured  and  offered 
for  sale. 

Babcock  and  Farrington  describe  a  milk-sediment  test 
devised  by  them  in  which  one  pint  of  milk  is  placed  in  a 


SANITARY  EXAMINATION  OF  MILK  125 

steam-heated  jacketed  container,  and  filtered  through  a 
disk  of  absorbent  cotton,  said  cotton  to  be  free  from  sizing 
or  starch,  which  prevents  satisfactory  filtering  of  the  milk. 
Milk  may  be  graded  according  to  the  degree  of  discolora- 
tion of  the  cotton. 

Leucocytes  in  Milk.  —  In  the  milk  of  normal,  healthy 
cows  may  be  found  a  number  of  leucocytes  or  white-blood 
corpuscles.  The  mixed  milk  from  a  healthy  herd  seldom 
contains  more  than  500,000  cells  per  cubic  centimeter, 
although  this  number  is  often  exceeded  in  the  milk  of  indi- 
vidual cows.  An  inflamed  or  diseased  condition  of  the 
udder  causes  a  great  increase  in  the  leucocyte  content  of 
the  milk,  hence,  at  the  present  time,  milk  containing  over 
500,000  of  these  bodies  per  cubic  centimeter  is  looked  upon 
as  coming. from  a  bruised  or  inflamed  udder  and  is  con- 
sidered unfit  for  food.  However,  this  number  cannot  be 
adopted  as  a  set  standard,  but  it  is  well  to  class  all  milk  as 
suspicious  when  it  does  exceed  this  limit.  A  physical  exami- 
nation of  the  cows  producing  the  milk  should  be  made  and 
action  taken  according  to  the  findings  at  this  examination. 

Fibrin  has  been  found  to  accompany  leucocytes,  es- 
pecially in  acute  cases.  Professor  Doane  found  that  when 
a  cow's  udder  is  badly  inflamed  these  fine  threads,  or  fibrin, 
are  found  in  the  milk.  The  leucocytes  in  such  milk  also 
tend  to  hang  together  in  clusters.  In  some  experiments 
with  milk  from  an  inflamed  udder,  Doane  found  as  many  as 
20,000,000  leucocytes  per  cubic  centimeter  of  milk.  Fibrin 
was  also  found  in  this  milk.  As  the  cow's  udder  became 
well,  the  number  of  leucocytes  dropped  to  500,000  per  cubic 
centimeter.  At  this  period,  the  fibrin  disappeared.  A 
number  of  counts  were  made  from  milk  of  different  cows, 
and  it  was  found  that  fibrin  accompanied  a  large  number 
of  leucocytes. 


126  DAIRY  TECHNOLOGY 

Reduction-Fermentation  Test.  —  This  test  was  origi- 
nated by  Barthel  of  the  Swedish  Experiment  Station  and 
is  used  as  follows:  To  20  .cubic  centimeters  of  milk  add 
0.5  cubic  centimeter  methylene  blue  and  2.5  per  cent  satu- 
rated alcoholic  solution  in  water.  Keeping  the  samples  at 
about  one  hundred  degrees  F.,  the  rapidity  of  the  reduc- 
tion of  the  color,  the  change  from  blue  to  white,  varies 
directly  as  the  number  of  bacteria  in  the  milk.  This  re- 
duction test  is  combined  with  the  fermentation  test  by 
keeping  the  samples  until  curdling  takes  place  and  noting 
the  time  required  to  curdle  and  the  presence  of  gas  or  bad 
flavors  in  the  curd. 

According  to  Barthel,  if  the  milk  contains  several  hundred 
thousand  bacteria  per  cubic  centimeter,  reduction  will  take 
place  within  fifteen  minutes.  If  the  blue  color  disappears 
within  an  hour,  the  milk  is  not  first  class.  One  to  three 
hours  are  required  for  the  reduction  in  high-grade  market 
milk,  but  even  a  greater  length  of  time  is  required  for  very 
fresh,  clean  milk. 

Of  course,  this  test  is  merely  an  indication  of  the  numoer 
of  bacteria  present,  but  it  may  be  found  very  useful  to  the 
dealer  trying  to  buy  a  high-grade  milk,  or  to  the  butter 
or  cheese  maker,  who  wishes  to  guard  against  the  evils  of 
over-ripe  milk. 


CHAPTER    XIII. 

WHIPPING  OF  CREAM. 

Conditions  Affecting  Viscosity  of  Cream.  —  When  cream 
is  pasteurized,  heated,  or  even  warmed,  the  clusters  of 
fat  globules  are  broken  up.  This  lessens  the  viscosity 
of  the  cream  to  such  an  extent  that  it  does  not  whip  so 
readily.  It  has  the  consistency  of  raw  cream  of  a  lower 
per  cent  of  fat.  This  frequently  misleads  the  consumer  to 
think  the  cream  is  not  up  to  standard  in  fat.  The  vis- 
cosity may  be  restored  by  holding  the  cream  at  a  low  tem- 
perature for  a  day,  or  at  least  12  hours,  but  this  is  not 
practicable  in  city  milk  supply.  Another  way  to  restore 
the  viscosity  to  cream  as  investigated  by  the  Wisconsin 
Experiment  Station  is  to  add  sucrate  of  lime,  known 
commercially  as  "  Viscogen."  Cream  containing  visco- 
gen  must  be  so  labeled  because  our  pure  food  laws  forbid 
the  addition  of  any  substance  to  milk  or  cream.  The  name 
"  visco-cream  "  has  been  used  to  designate  this  product. 
Preparing  Viscogen.  —  Viscogen  may  be  made  as  follows : 
Dissolve  i\  parts  granulated  sugar  in  5  parts  water; 
slake  i  part  good  rock-lime  in  3  parts  water.  Pour  the 
slaked  lime  through  a  wire  strainer  to  remove  coarse, 
undissolved  particles  and  add  to  the  sugar  solution. 
Agitate  the  mixture  occasionally  for  two  to  three  hours, 
then  allow  it  to  settle  for  about  twelve  hours  or  until  the 
liquid  becomes  clear,  when  it  can  be  siphoned  off  and  is 

ready  for  use. 

127 


128  DAIRY  TECHNOLOGY 

Viscogen  should  be  kept  in  air-tight  containers,  be- 
cause, when  exposed,  it  absorbs  carbon  dioxide  from  the 
air  and  is  weakened.  Exposure  to  the  air  for  a  long  time 
also  darkens  the  solution,  but  this  does  not  impair  its 
usefulness. 

The  function  of  sugar  in  viscogen  is  to  hold  lime  in 
solution.  A  sugar  solution  of  equal  parts  of  sugar  and 
water  will  hold  about  one  hundred  times  as  much  lime 
as 'is  found  in  plain  lime  water. 

Use  of  Viscogen  in  Cream.  —  One  part  of  viscogen  to 
from  one  hundred  to  one  hundred  and  fifty  parts  of  cream 
will  produce  the  desired  results.  An  excess  of  this 
substance  imparts  a  soapy  flavor  to  the  cream,  hence 
the  following  method  of  adding  viscogen  is  recom- 
mended. 

Titrate  a  small  quantity  of  cream  with  the  viscogen 
that  is  to  be  used,  and  calculate  the  quantity  of  viscogen 
required  to  neutralize  (to  phenolphthalein)  all  of  the  acid 
in  the  cream;  then  add  from  one-half  to  two- thirds  this 
quantity. 

For  example:  We  have  800  pounds  of  25  per  cent 
cream,  pasteurized.  We  wish  to  restore  its  viscosity  by 
the  addition  of  viscogen.  Put  some  of  the  viscogen  into 
a  burette  graduated  in  cubic  centimeters,  such  as  is  used 
for  Manns'  acid  test.  Place  a  sample  of  cream,  35  cubic 
centimeters,  or  any  convenient  amount,  in  a  white  cup, 
add  two  or  three  drops  of  phenolphthalein,  and  then  run 
in  viscogen  from  the  burette  until  a  permanent  faint  pink 
color  is  secured.  If  the  quantity  of  viscogen  used  to 
neutralize  the  acid  in  35  cubic  centimeters  of  cream  was 
0.6  cubic  centimeter,  then  to  neutralize  the  acid  in  800 
pounds  of  cream  would  require: 

35  :  0.6  ::  800  :  x    or    13.7  pounds. 


WHIPPING  OF  CREAM  129 

But  we  wish  to  neutralize  only  one-half  of  the  acid  in  the 
cream,  so  we  require  but  one-half  of  13.7  or  6.8  pounds  of 
viscogen. 

Pasteurized  cream  should  be  cooled  to  60°  F.  or  less 
before  the  viscogen  is  added;  this  is  to  avoid  the  produc- 
tion of  an  undesirable  alkaline  flavor. 

The  retailer  of  cream  and  the  consumer  should  both  be 
well  posted  on  the  influence  of  various  conditions  on  the 
whipping  quality  of  cream. 

The  greater  the  per  cent  of  fat  in  cream,  the  better 
the  cream  will  whip;  but  an  excess  of  fat  is  not  necessary 
or  even  desirable,  and,  if  proper  conditions  are  secured, 
cream  containing  25  to  30  per  cent  of  fat  can  be  whipped 
until  it  stands  alone. 

Other  conditions  being  observed  the  colder  the  cream 
(freezing  point  being  the  limit)  the  better  it  will  whip. 
This  is  a  very  important  point  for  the  cook  to  observe, 
because  cream  that  will  produce  an  excellent  whip  at  50°  F. 
can  be  only  fair  when  whipped  at  60°  F.  Failure  to  secure 
a  good  whip  is  too  often  due  to  the  warming  of  the 
cream  during  the  whipping;  cream  at  50°  F.  brought  into 
a  warm  kitchen,  placed  in  a  warm  dish,  and  having  warm 
air  beaten  into  it,  will  possibly  acquire  a  temperature 
of  65°  to  70°.  Under  such  conditions  it  is  doubtful  if  the 
whipping  will  produce  good  results;  but  if  the  same  cream 
be  whipped  in  a  cold  vessel,  in  a  cool  room,  much  better 
results  will  be  secured. 

Cream  24  hours  old  will  whip  better  than  fresh  cream. 
This  is  due  to  the  blending  together  of  the  various  milk 
components,  and  to  the  gathering  of  the  fat  globules  into 
clusters  which  increase  the  viscosity  of  the  cream.  The 
same  result  may  be  secured  to  a  certain  extent  by  the 
addition  of  viscogen, 


130  DAIRY  TECHNOLOGY 

C.  W.  Melick  1  notes  the  following  points  affecting  the 
whipping  of  cream: 

"  i.  There  was  no  difference  in  the  whipping  qualities 
of  gravity  and  separator  cream.  When  any  difference  is 
experienced  it  is  due  to  other  factors  and  not  to  the  method 
of  getting  the  cream  from  milk. 

2.  Cream    for    whipping   purposes    should    contain    at 
least  20  per  cent  butterfat.     The  results  were  obtained 
with  cream  containing  from  25  per  cent  to  40  per  cent 
butterfat. 

3.  For  best  results  cream  should  be  held  at  as  low  a 
temperature  as  possible  (35°  to  45°  F.)  for  at  least  two 
hours  before  whipping,  and  should  be  whipped  in  a  cool 
room. 

4.  For  good  results   cream  should  be  from   12   to   24 
hours  old.     This  gives  an  opportunity  for  the  develop- 
ment of  a  small  amount  of  acid  in  the  cream.     The  acid 
effected  a  gelatinous  consistency  in  the  casein  and  albumin 
and  thus  facilitated  the  incorporation  of  air  in  whipping. 
When  it  is  desired  to  whip  fresh  cream,  ^o  Per  cen^  commer- 
cial lactic  acid  may  be  added  to  take  the  place  of  the  acid 
which  would  develop  by  setting  the  cream  from  12  to  24 
hours. 

5.  Pasteurized  cream  may  be  whipped  as  easily  as  un- 
pasteurized  cream  if  it  is  thoroughly  cooled  and  held  at 
35°  to  45°  F.  for  at  least  two  hours  before  whipping. 

6.  For  good  results  cream  should  whip  in  from  30  to 
60  seconds.     When  a  longer  time  is  required  there  is  danger 
of  some  of  the  butterfat  separating  or  churning. 

7.  The  addition  of  one- tenth  per  cent  of  commercial 
lactic  acid  to  cream  facilitated  its  whipping  and  made 
it  possible  to  whip  cream  which  was  fresher,  which  con- 
tained less  butterfat  and  which  was  warmer  than  is  ad- 
visable for  the  best  results. 

8.  The  use  of  viscogen  facilitated  the  whipping  of  cream 
to  a  greater  extent  than  any  other  ingredient  with  the 
exception  of  lactic  acid.     It  proved  less  effective  than  the 

1  Maryland  Bui.  136. 


WHIPPING  OF   CREAM  131 

latter  and  also  less  effective  than  a  low  temperature. 
The  addition  of  viscogen  caused  cream  to  remain  sweet 
from  12  to  24  hours  longer  than  it  otherwise  would. 

9.  The  use  of  powdered  sugar,   powdered  milk,   salt, 
caramel,    gelatine,    junket,    and    corns  tar  ch,    each    facili- 
tated the  whipping  of  cream  to  a  small  degree,  and  each 
to  practically  the  same  extent.     None  of  them  proved 
as  effective  as  a  low  temperature  and  the  development 
or  addition  of  lactic  acid.     The  addition  of  an  excess  of 
gelatine  above  10  per  cent,  or  of  cornstarch  above  20  per 
cent  caused  a  lumpy  cream  when  whipped. 

10.  The  use  of  egg  albumen  with  cream  when  whipped 
separately  and  mixed,  produced  a  lighter  foam,  but  had 
no  effect  upon  the  time  required  to  whip.     When  mixed 
before  the  egg  albumen  was  whipped,   at  temperatures 
above  40°  F.,  the  whipping  was  retarded. 

11.  The  use  of  vanilla  extract  used  in  ordinary  quan- 
tities had  no  effect  upon  the  whipping  qualities  of  cream. 

12.  The  charging  of  cream  with  carbonic  acid  gas  with- 
out pressure  had  no  effect  on  its  whipping  qualities  but 
caused  it  to  remain  sweet  from  12  to  24  hours  longer. 

13.  The  use  of  cream  from  cows  near  the  end  of  their 
lactation   period   whipped   with   slightly   more    difficulty 
than  did  cream  from  fresh  cows. 

14.  Whipped  cream  will  not  keep  sweet  as  long  as  un- 
whipped  cream. 

15.  When  any  additions  are  made  to  cream  to  facili- 
tate whipping  it  should  be  so  labeled  as  to  not  deceive  the 
purchaser." 


PART    III. 

ICE-CREAM    MAKING. 
CHAPTER  XIV. 

HISTORY  AND  EXTENT  OF  ICE-CREAM  MAKING. 

ALEXANDER  THE  GREAT  is  said  to  have  been  very  fond  of 
iced  beverages,  and  it  is  said  that  one  of  our  modern  vari- 
eties, the  "Macedoine,"  was  named  after  the  ancient  Mace- 
donian. Wines  and  fruit  juices  were  cooled  with  ice  and 
snow  at  the  courts  of  France  and  Italy  in  very  early  times. 
When  and  where  the  first  water  ices  were  made  no  one  can 
say,  but  it  seems  probable  that  they  were  brought  to  France 
from  Italy  by  Catherine  de  Medici  in  the  sixteenth  cen- 
tury. Marco  Polo  is  reported  to  have  brought  recipes  for 
water  ice  and  milk  ice  from  Japan  in  the  thirteenth  century. 

Cream  ice  was  served  at  a  banquet  given  by  Charles  I  of 
England.  This  ice  was  made  by  a  French  cook  named  De 
Mireo,  and  it  is  related  that  the  king  was  so  well  pleased 
with  the  new  dish  that  he  pensioned  the  cook  with  20  pounds 
a  year  on  condition  that  the  latter  should  not  make  the 
ice  for  any  one  but  the  king,  and  should  tell  no  one  else  how 
to  make  it. 

English  cook  books,  published  about  the  middle  of  the 
eighteenth  century,  gave  recipes  for  making  cream  ices. 

It  can  readily  be  seen  how  the  making  of  ice  cream  has 
developed  step  by  step  from  the  cooling  of  wines  and  fruit 

132 


HISTORY  AND  EXTENT  OF  ICE-CREAM  MAKING       133 

juices  to  the  freezing  of  similar  liquids,  and  then  to  the 
freezing  of  milk  and  cream. 

Ice  cream  is  said  to  have  been  introduced  to  the  city  of 
Washington,  by  Mrs.  Alexander  Hamilton,  at  a  dinner 
that  was  attended  by  George  Washington. 

The  first  ice  cream  advertisement  on  record  is  one  that 
appeared  in  the  "  Post  Boy,"  New  York  City,  June  8, 


FIG.  30.  —  View  of  large  ice  cream  plant.     (Ice  Cream  Trade  Journal.) 

1786.     At  this  time,  ice  cream  sold  readily  at  one  dollar 
per  quart. 

Jacob  Fussell,  so  far  as  known,  was  the  first  man  to  make 
a  wholesale  business  of  ice-cream  making.  He  was  a  milk 
dealer  in  Baltimore,  Md.,  and  adopted  ice-cream  making 
to  utilize  his  surplus  cream.  A  few  years  later,  an  ice 
company,  becoming  interested  in  the  manufacture  of  ice 
cream,  paid  Fussell  $500  for  teaching  one  of  their  men  the 
art  of  making  this  product. 


134  DAIRY  TECHNOLOGY 

American  enterprise  took  up  the  new  industry,  and  it 
developed  steadily.  However,  it  was  not  until  after  1890 
that  the  rapid  growth  began.  Since  that  date  the  business 
has  been  growing  with  increasing  rapidity,  aided,  to  some 
extent,  by  the  perfection  of  artificial  refrigeration.  This 
provided  a  way  for  these  frozen  dainties  to  be  used  in  the 
south,  and  made  possible  the  great  wholesale  factories 
found  in  some  of  our  large  cities. 

The  value  of  the  ice  cream  consumed  in  this  country 
has  reached  the  enormus  figure  of  $i5o,ooo,ooo1  per  annum 
and  has  outgrown  the  small  and  secret  chamber  in  which 
the  manufacturer  of  a  few  years  ago  performed  his  work. 

The  making  of  ice  cream  has  been  regarded,  at  least  in 
part,  as  a  secret  process.  During  the  few  years  that  ice 
cream  has  been  made  on  a  commercial  scale,  and  even  to- 
day, in  many  places,  the  mixing  and  freezing  of  ice  cream 
are  carried  on  behind  locked  doors,  too  often  in  cellars. 
But  it  is  the  opinion  of  many  of  the  large  manufacturers 
that  the  time  has  come  when  secrecy  is  not  necessary,  nor 
even  desirable.  The  making  of  ice  cream  in  secret  does 
not  create  a  monoply  for  the  manufacture,  nor  does  it 
increase  the  popularity  of.  or  demand  for  the  product.  On 
the  other  hand,  the  making  of  ice  cream  in  a  modern, 
properly  constructed,  sanitary  factory,  open  to  the  public, 
is  a  great  advertisement  for  the  manufacturer  and  is  con- 
ducive to  an  increased  demand  for  the  product.  Manu- 
facturers of  ice-cream  supplies  are  scattering  broadcast 
exact  directions  for  making  the  mix,  freezing  the  cream,  etc. 
Several  dairy  schools  are  teaching  commercial  ice-cream 
making.  Some  large  dealers  are  promulgating  the  opinion 
that  ice-cream  making  is  a  scientific  process,  and  that  the 

1  John  Gordon  —  Address  at  Second  Annual  Convention  of  Iowa  Ice 
Cream  Makers'  Association. 


HISTORY  AND   EXTENT  OF   ICE-CREAM   MAKING      135 

more  the  subject  is  made  public,  is  discussed  and  studied, 
the  more  perfect  will  the  process  become  and  the  better 
will  the  product  be.  The  better  the  product,  the  greater 
the  consumption  of  the  same. 

Classification  of  Ice  Creams  and  Ices.  —  Ice  creams  may 
be  divided  into  many  classes.  Their  differences  are  some- 
what indefinite.  However,  there  are  three  great  divisions 
commonly  known  and  recognized  throughout  this  country. 
These  are: 

I.  Philadelphia  Ice  Cream. 

Made  up  of  cream,  sugar,  flavoring,  and  usually  a 
binder.  Under  this  heading  the  following  would  be 
included:  Plain  ice  cream,  nut  ice  cream,  fruit  ice 
cream,  chocolate  ice  cream,  coffee  ice  cream,  macaroon 
ice  cream,  etc. 

II.  Neapolitan  Ice  Cream. 

This  differs  from  the  first  class  chiefly  in  that  it 
always  contains  eggs.  This  kind  of  ice  cream  admits 
of  wide  varieties  and  may  resemble  in  composition  and 
consistency  a  frozen  pudding  more  than  an  ice  cream. 

III.  Fancy  Ice  Cream. 

This  kind  of  ice  cream  differs  chiefly  from  the 
Philadelphia  Ice  Cream  in  the  manner  of  molding  or 
printing,  and  in  the  coloring. 

1.  Brick  Ice  Cream. 

This  is  usually  made  up  in  pint,  quart  and  two- 
quart  sizes.  It  is  made  in  layers.  Any  of  the  ice 
creams  may  be  used  for  this  purpose. 

2.  Individual  Molds. 

These  molds  are  shaped  to  imitate  some  object 
(fruit  or  animal).  The  ice  cream  object  may  be 
colored  in  imitation  of  the  object  it  represents. 


136  DAIRY  TECHNOLOGY 

Associated  with  ice  cream  are  numerous  other  ices, 
none  of  which,  however,  are  dairy  products.  These  are 
usually  considered  under  the  following  heads. 

IV.    Ices. 

1.  Water  ice  is  fruit  juice  diluted  with  water  to  the 
proper  degree,  sweetened  and  frozen  the  same  as  is  ice 
cream.     Its  texture  is  quite  different  from  that  of  ice 
cream.    The  latter  is  smooth  and  velvety,  while  the  former 
is  grainy,  being  more  like  firm,  wet  snow  in  texture. 

2.  Sherbet    sometimes    closely  resembles    ice    cream 
in  appearance,  body,  and  texture.    However,  no  cream  or 
milk  is  used  in  this  ice.     Its  creamy  appearance  is  due 
to  the  presence  of  beaten  white  of  egg,  gelatin,  or  other 
binders.     Sherbet  is  composed  of  fruit  juice,  water,  sugar, 
white  of  egg,  and,  sometimes,  a  binder.     If  beaten  vio- 
lently until  frozen  hard  the  result  will  be  a  fine,  smooth, 
creamy  ice.     If  frozen  with  but  slight  agitation  or  only 
half  frozen,  the  result  will  be  a  more  granular  texture. 

3.  Sorbet  is  a  name  sometimes  applied  to  sherbets 
of  fine,  smooth  texture. 

4.  Granites  are  water  ices  only  half  frozen  without 
much  stirring,  having  a  coarse  icy  texture. 

5.  Frozen  Punches  are  made  by  adding  one  or  more 
liquors  or  cordials  like  champagne,  maraschino,  Jamaica 
rum,  etc.,  usually  after  the  freezing  is  nearly  or  entirely 
completed. 

The  following  classification  has  been  adopted  by  Prof. 
Mortensen  at  the  Iowa  Experiment  Station:1 

I.   Plain  Ice  Creams. 
II.   Nut  Ice  Creams. 
III.   Fruit  Ice  Creams. 

1  Ames,  Iowa  Bui.  123. 


HISTORY  AND  EXTENT  OF  ICE-CREAM  MAKING      137 

IV.  Bisque  Ice  Creams. 
V.   Parfaits. 
VI.   Mousses. 
VII.   Puddings. 
VIII.  Aufaits. 
IX.  Lactos. 
X.  Ices. 

1.  Sherbets. 

2.  Milk  Sherbets. 

3.  Frappes.   • 

4.  Punches. 

5.  Souffles. 

I.  Plain  ice  cream  is  a  frozen  product  made  from 
cream  and  sugar  with  or  without  a  natural 
flavoring. 

II.  Nut  ice  cream  is  a  frozen  product  made  from 
cream,  sugar  and  sound,  non-rancid  nuts. 

III.  Fruit  ice  cream  is  a  frozen  product  made  from 

cream,  sugar  and  sound,  clean,  mature  fruits. 

IV.  Bisque  ice  cream  is  a  frozen  product  made  from 

cream,  sugar  and  bread  products,  marshmallows 

or  other  confections,  with  or  without  natural 

flavoring. 
V.   Parfait  is  a  frozen  product  made   from  cream, 

sugar  and  egg  yolks,  with  or  without  nuts  or 

fruits  and  other  natural  flavoring. 
VI.   Mousse   is   a   frozen   whipped   cream   to   which 

sugar  and  natural  flavoring  have  been  added. 
VII.   Pudding  is  a  product  made  from  cream  or  milk, 

with  sugar,  eggs,  nuts  and  fruits,  highly  flavored. 
VIII.  Aufait  is  brick  cream  consisting  of  layers  of  one 

or  more  kinds  of  cream  with  solid  layers  of 

frozen  fruit. 


138  DAIRY  TECHNOLOGY 

IX.  Lacto  is  a  product  manufactured  from  skimmed 
or  whole  sour  milk,  eggs  and  sugar,  with  or 
without  natural  flavoring. 

X.  Ices  are  frozen  products  made  from  water  or 
sweet  skimmed  or  whole  milk  and  sugar,  with 
or  without  eggs,  fruit  juices,  or  other  natural 
flavoring. 

Ices  may,   for  convenience,   be  divided  into  sherbets, 
milk  sherbets,  frappes,  punches  and  souffles. 

1.  Sherbet    is    an    ice    made    from   water,    sugar,    egg 
albumen  and  natural  flavoring,  and  frozen   to   the  con- 
sistency of  ice  cream. 

2.  Milk  sherbet  is  an  ice  made  from  sweet  skimmed 
or  whole  milk  with  egg  albumen,  sugar  and  natural  flavor- 
ing, frozen  to  the  consistency  of  ice  cream. 

3.  Frappe  is  an  ice  consisting  of  water,  sugar  and  natural 
flavoring,   and  frozen  to  a  soft  semi-frozen  consistency. 
Same  formulas  as  are  given  for  sherbets  will  answer  for 
frappe  by  omitting  the  egg  albumen. 

4.  Punch  is  a  sherbet  flavored  with  liquors,  or  highly 
flavored  with  fruit  juices  and  spice. 

5.  Souffle  is  an  ice  made  from  water,  eggs,  sugar    and 
flavoring   material.     It   differs   from   sherbets   mainly   in 
that  it  contains  the  whole  egg. 


CHAPTER  XV. 
CREAM  FOR  ICE-CREAM  MAKING. 

IN  the  manufacture  of  ice  cream,  the  best  cream  to  use 
is  perfectly  sweet,  fresh  cream.  Cream  of  the  highest 
quality  must  be  produced  by  healthy  cows,  properly  fed 
and  cared  for  under  perfectly  sanitary  conditions.  It 
must  be  handled  only  in  clean  containers,  kept  cold  and 
delivered  daily  to  the  factory. 

Too  much  emphasis  cannot  be  placed  upon  the  subject 
of  quality  of  cream.  Ice  cream  is  valued  mainly  because 
of  its  pleasing  flavor  and  refreshing  effect.  Hence  the  pres- 
ence of  any  undesirable  flavor  is  much  more  objectionable 
in  this  product  than  in  other  staple  foods. 

Acidity.  —  An  acidity  of  the  cream  above  0.25  per  cent 
is  too  great  for  ice-cream  making,  and  should  not  be  used 
at  all,  or  it  may  be  reduced  by  the  addition  of  very  sweet 
cream.  In  dire  need,  cream  not  too  sour  and  old  may  be 
partly  reduced  in  acidity  by  adding  some  harmless  neu- 
tralizer.  Ice-cream  made  from  such  raw  material  should 
be  labeled  accordingly.  The  acidity  of  the  cream  may  be 
reduced  two-tenths  per  cent  without  greatly  impairing  the 
flavor,  but  too  great  an  addition  of  alkali  must  be  avoided 
because  of  the  abnormal  flavor  it  imparts  to  the  cream. 
An  excess  of  alkalinity  is  more  objectionable  than  slightly 
acid  cream.  When  reducing  the  acidity  of  cream,  it  is  best 
to  use  an  acid  test,  calculate  the  amount  of  neutralizer 
required,  and  add  just  enough  to  bring  the  per  cent  acid 
to  the  point  desired,  not  lower  than  to  0.2  per  cent  acid. 

139 


140  DAIRY  TECHNOLOGY 

One  part  of  viscogen  to  180  parts  of  cream  will  reduce 
the  acidity  of  the  cream  about  o.i  per  cent. 

Homogenized  Cream.  —  The  process  of  homogeniza- 
tion  consists  of  passing  heated  cream  (140°  F.  to  180°  F.), 
through  a  machine  known  as  a  homogenizer.  The  func- 
tion of  the  machine  is  to  break  the  fat  globules  into  such 
tiny  particles  that  they  cannot  be  separated  from  the  serum 
by  gravity  nor  even  by  centrifugal  force,  except  to  a  small 
extent.  This  insures  an  absolutely  uniform  emulsion  of 
all  the  solids  in  the  cream.  Another  effect  of  this  process 
is  a  great  increase  in  the  viscosity  of  the  cream.  Homo- 
genized cream  containing  fourteen  per  cent  fat  has  about  the 
same  consistency  as  fresh,  raw  cream  containing  18  per 
cent  fat. 

Homogenized  cream  may  be  produced  in  three  different 
ways: 

(1)  By  using  natural  cream. 

(2)  By  mixing  skim  or  whole  milk  and  butter  in  such 
proportions  that  the  resulting  product  will  be  cream  of  the 
desired  per  cent  of  fat. 

(3)  By  mixing  butter,  milk  powder  and  water  in  such 
proportions  that  the  resulting  mixture  will  have  approxi- 
mately the  same  composition  as  a  natural  cream. 

Some  large  ice-cream  manufacturers  store  quantities 
of  unsalted  "  June  Extras"  butter  to  be  used  in  the  busy 
season,  when  it  is  difficult  to  secure  an  ample  supply  of 
fresh  cream. 

Pasteurization.  —  The  thorough  pasteurization  of  sweet 
cream  destroys  about  ninety-nine  per  cent  of  the  bacteria 
present,  and  hence  causes  the  cream  to  keep  sweet  a  much 
longer  time.  But  the  heating  of  the  cream  breaks  down 
the  clusters  of  fat  globules,  renders  the  cream  less  viscous, 
and  apparently  poorer  or  lower  in  fat  content.  The  ice- 


CREAM  FOR  ICE-CREAM  MAKING,  141 

cream  maker  desires  a  thick,  viscous  cream,  so  he  generally 
objects  to  pasteurization.  It  has  been  found  that  when 
cream  is  allowed  to  stand  at  a  low  temperature  (about 
40°  F.)  for  24  hours  after  pasteurization,  it  yields  as  large 
a  volume  of  good  bodied  ice  cream  as  does  raw  cream  kept 
under  similar  temperature  conditions  for  the  same  length 
of  time.  Hence  pasteurized  cream  may  be  used  successfully 
in  ice-cream  making,  if  it  is  allowed  to  reestablish  its 
viscosity. 

Aging  and  Cooling.  —  It  is  a  recognized  fact  among  ice- 
cream makers  that,  in  order  to  obtain  the  proper  yield  and 
texture,  it  is  necessary  to  hold  the  cream  over  night,  and 
even  for  24  hours,  at  a  low  temperature  before  freezing. 
During  this  time  its  viscosity  is  greatly  increased.  It  is 
especially  important  to  age  pasteurized  cream  in  order  to 
secure  good  results.  Cream  that  is  to  be  held  for  24  hours 
must  be  kept  cold,  first,  in  order  to  prevent  souring,  and 
second  to  increase  the  viscosity.  Cream  with  such  charac- 
teristics produces  ice  cream  which  has  better  body  and  tex- 
ture, just  as  butter  has  a  better  grain  and  body  if  the 
cream  is  held  at  a  low  temperature  for  two  or  more  hours 
before  churning. 

When  aging  cream,  the  aim  should  be  to  keep  it  as  cold  as 
possible  without  freezing.  This  can  be  done  most  readily 
by  placing  the  cans  of  cream  in  a  well-covered  and  well- 
insulated  tank  containing  a  mixture  of  water,  ice  and  some 
salt. 

Fat  Content. —  From  the  quality  standpoint,  the  ideal  per 
cent  of  fat  in  cream  for  ice-cream  making  is  about  twenty, 
(before  the  sugar,  etc.,  is  added,  or  fourteen  to  seventeen 
per  cent  in  the  mix).  A  much  richer  cream  than  this  is 
likely  to  be  too  rich  and  buttery.  Some  people  like  the 
flavor  of  extra  rich  cream,  but  most  prefer  ice  cream  of 


142  DAIRY  TECHNOLOGY 

medium  richness.  A  large  dish  of  exceedingly  rich  ice 
cream  is  likely  to  cause  indigestion,  and  a  smaller  quantity 
of  it  is  consumed.  Insufficient  fat  in  the  cream,  unless  an 
excess  of  filler  is  used,  produces  a  coarse  granular  icy  tex- 
ture, which  is  not  desirable,  and  a  lower  overrun  is  also  ob- 
tained from  such  cream.  From  a  health  standpoint  ice 
cream  containing  about  fourteen  per  cent  of  fat  is  prefer- 
able. From  such  cream,  good  palatable  ice  cream  having  a 
desirable  body  can  be  obtained.  A  proper  overrun  can  also 
be  obtained  from  cream  of  this  richness. 

From  the  manufacturer's  standpoint,  a  low  fat  content 
may  seem  desirable.  At  places  where  ice  cream  is  sold 
without  the  maker's  name  being  known,  and  without  legal 
restrictions,  we  find  ice  cream  containing  as  low  as  four  to 
six  per  cent  of  fat.  This  is  commonly  known  as  circus  or 
picnic  ice  cream.  However,  the  manufacturer  trying  to 
establish  a  favorable  market  for  his  goods  must  produce 
the  best  possible  quality. 

National  and  some  state  laws  specify  that  ice  cream  shall 
contain  a  certain  per  cent  of  butter  fat,  usually  fourteen 
per  cent. 


CHAPTER   XVI. 

PREPARING  THE  MIX.     FILLERS  AND   BINDERS. 

Flavor.  —  The  flavor  of  ice  cream  is  dependent  chiefly 
upon  three  things:  the  cream  itself,  the  flavoring  extract 
or  fruit  added,  and  the  sugar. 

The  necessity  for  good-flavored  cream  for  ice-cream  mak- 
ing has  already  been  discussed. 

The  kinds  of  flavoring  extracts  that  may  be  used  are 
too  numerous  to  mention.  The  quantity  will  depend  upon 
the  brand  used.  The  concentration  of  extracts  varies 
widely,  and  it  is  notable  that  the  same  firm  occasionally 
makes  single,  double  and  triple  strength  extracts.  Hence 
it  is  a  good  practice  to  find  one  suitable  extract  and  use 
that  brand  exclusively;  but  most  important  of  all  is  to 
have  the  very  highest  quality  of  extract  that  can  be  ob- 
tained. The  different  kinds  of  flavoring  substances  may 
be  grouped  as  follows : 

1.  Crushed  fruits  with  their  juices. 

2.  Extract  flavorings. 

3.  Sweetening. 

i.  The  crushed  fruits  of  the  various  kinds  are  at  all 
times  to  be  preferred.  These,  however,  are  not  always 
obtainable,  and  when  out  of  season  they  are  expensive. 
For  these  reasons,  the  crushed  fruits  cannot  always  be  used 
for  flavoring  ice  cream.  The  extract  flavorings  are  used 
largely  in  connection  with  the  manufacturing  of  ice  cream 
on  a  commercial  scale.  When  ice  cream  is  manufactured 

143 


144 


DAIRY  TECHNOLOGY 


for  home  use,  in  a  small  way,  crushed  fruits  are  to  be  pre- 
ferred. During  the  season  that  ice  cream  is  manufactured 
on  a  small'scale,  fresh  fruits  are  usually  obtainable.  About 
two  ounces  of  crushed  fruit  to  each  pound  of  cream  will  be 
found  to  produce  the  proper  flavor.  The  amount  will  vary 
a  little"according  to  the  likes  and  dislikes  of  the  consumer 
and  according  to  the  degree  of  concentration  of  the  fruit. 


FIG.  31.  —  The  Wizard  ice  cream  mixer. 

The  crushed  fruit  may  be  added  to  the  cream  just  pre- 
vious to  putting  it  into  the  freezing  can,  but  at  this  time 
there  is  some  danger  of  coagulating  the  cream.  The  acid 
in  the  fruit  affects  the  cream  to  some  extent.  It  is  pref- 
erable to  add  the  crushed  fruit  and  juice  to  the  ice  cream 
after  it  has  been  partially  frozen.  As  it  begins  to  appear 
thick,  the  freezer  is  stopped  and  the  crushed  fruit  added. 
At  this  stage,  the  ice  cream  is  not  so  stiff  that  the  fruit 
cannot  be  properly  mixed  with  it  and  there  is  little  or  no 
danger  of  coagulating  the  cream. 


PREPARING  THE   MIX.     FILLERS   AND  BINDERS      145 

2.  The  extract  flavorings  are  used  largely  in  commercial 
ice-cream  making,  chiefly  because  they  are  easily  obtained, 
relatively  cheap,  and  can  be  stored  without  spoiling. 
Some  ice-cream  makers  claim  that  some  of  these  extract 
flavorings  impart  disagreeable  flavors  to  the  ice  cream.  So 
far  as  the  authors'  experience  goes,  this  claim  cannot  be 
substantiated,  The  poorer  grades  of  extracts  should  never 


FIG.  32.  —  The  Miller  ice  cream  mixer. 

be  used.  Supply  houses  keep  several  grades,  and  the  best 
grade  of  flavoring  extracts  should  invariably  be  added  to 
the  cream.  The  amount  of  flavoring  extract  to  be  used 
depends  upon  the  degree  of  concentration  of  the  extract. 
If  the  best  extract  is  secured,  one  ounce  to  one  gallon  of 
cream  or  two  small  tablespoonfuls  for  every  gallon  of  cream 
used  is  about  the  proper  amount.  The  extract  should 
ordinarily  not  be  added  until  just  previous  to  putting  the 
mix  into  the  freezing  can.  Especially  is  this  important 


146  DAIRY  TECHNOLOGY 

when  the  cream  is  pasteurized.  Pasteurization  is  likely 
to  drive  off  the  extract  flavors.  These  are  mostly  volatile. 
Some  of  the  oil-flavorings  are  not  so  volatile,  and  it  does 
not  matter  when  they  are  added. 

3.  The  quantity  of  sugar  used  in  making  plain  ice  cream 
is  usually  one  pound  of  sugar  to  six  of  cream.  The  sugar 
should  be  of  the  best  granulated  variety  and  must  be 
thoroughly  dissolved  before  freezing. 

"  Salt1  is  not  usually  added  to  ice  cream,  purposely,  at 
least;  but  careful  and  repeated  tastings  by  many  people 
proved  that  the  unbiased  consumer  prefers  a  cream  con- 
taining salt  at  the  rate  of  half  a  teaspoonful  per  gallon  of 
mixture  to  a  cream  which  is  not  thus  modified.  The  taste 
of  the  salt  as  such  does  not  become  evident  until  a  much 
larger  quantity  is  used." 

Fillers  and  Binders.  —  The  purpose  of  using  fillers  in 
ice-cream  making  is  to  give  the  product  a  firmer  body  with 
better  standing  up  qualities.  Fillers  do  not  necessarily 
increase  the  swell  and  may  even  lessen  it  when  large  quan- 
tities of  such  materials  are  used. 

Of  the  starchy  fillers  that  may  be  used,  rice  flour,  wheat 
flour  and  cornstarch  give  the  best  results,  because  of  the 
smallness  of  their  starch  grains.  Cornstarch  is  the  least 
desirable.  Starchy  fillers  must  be  thoroughly  cooked  be- 
fore being  added  to  the  cream.  If  this  is  not  done  the 
starch  grains  can  readily  be  detected  when  the  product  is 
eaten.  This  is  undesirable  in  a  high-grade  product. 

Condensed  milk  is  being  used  to  a  great  extent  in  ice- 
cream making,  and  with  very  satisfactory  results.  Some 
large  factories  have  their  own  condensing  machinery,  by 
means  of  which  they  not  only  make  their  own  filler,  but 
convert  any  surplus  milk  into  a  product  that  may  be 

1  Vermont  Bui.  155. 


PREPARING  THE  MIX.     FILLERS  AND   BINDERS       147 

stored  until  needed  in  their  factory  or  disposed  of  through 
other  channels.  Plain  evaporated  milk  in  bulk  is  the  grade 
of  condensed  milk  commonly  used  for  this  purpose. 

Egg  fillers  usually  are  not  used  in  low-grade  ice  cream 
because  they  are  expensive.  In  order  that  eggs  may  have 
the  desired  effect  upon  the  body  of  the  ice  cream,  they 
should  be  cooked.  This  is  done  by  mixing  the  beaten  eggs 
with  milk  or  cream,  then  cooking  it,  so  that  it  forms  a  thin 
custard.  Such  a  custard,  when  added  to  thin  cream  and 
frozen,  does  not  increase  in  volume  so  much  as  does  a 
normal  rich  cream. 

Rennet  is  sometimes  used  in  ice-cream  making,  but  has 
little  or  no  effect  unless  the  milk  or  cream  be  warm  when  the 
rennet  is  added  in  order  that  curdling  may  take  place. 
Under  these  conditions  the  product  shows  a  slightly 
smoother  texture  and  firmer  body.  Rennet  is  seldom  used 
in  commercial  ice-cream  making. 

Milk  powder  is  used  for  ice  cream  both  as  filler,  binder, 
and  batch. 

The  chief  functions  of  binders  in  ice  cream  are  to  bind 
the  materials  into  one  homogeneous  mass,  and  prevent 
water  crystals  from  forming  after  the  ice  cream  has  stood 
a  day  or  more.  Ice  cream  containing  a  binder  or  filler 
does  not  melt  readily  when  served. 

One  of  the  fillers  most  widely  used  for  this  purpose  is 
gelatin.  This  substance  is  prepared  for  use  by  dissolving 
it  in  hot  skim  milk  or  water,  and  stirring  quickly  into  the 
cream.  The  manufacturer  must  carefully  select  the  gelatin 
in  order  to  be  sure  that  it  is  perfectly  pure  and  sanitary. 
According  to  Washburn1  the  higher-priced  gelatin  is  cheaper 
in  the  end  than  the  low-priced  goods.  He  states  that 
three  and  a  half  to  four  pounds  of  high-grade  gelatin,  cost- 
1  Vermont  Bui.  155. 


148  DAIRY  TECHNOLOGY 

ing  about  a  dollar,  will  produce  the  same  results  as  will  six 
to  eight  pounds  of  a  cheaper  grade  costing  50  per  cent  more. 

At  the  present  time  gelatin  is  being  replaced  to  some 
extent  by  gum  tragacanth.  One  reason  for  this  change  is 
that  many  people  and  some  health  officers  object  to  the  use 
of  gelatin.  They  claim  that  it  may  be  dangerous  to  health, 
because  it  may  have  come  from  diseased  animals,  or  it 
may  have  been  contaminated  before  or  during  the  manu- 
facturing process.  Gum  tragacanth  is  perfectly  odorless 
and  is  very  satisfactory  as  a  binder,  even  in  very  small 
quantities.  Stock  may  be  made  up  as  follows:  "Dissolve 
i  ounce  of  gum  in  i  quart  of  hot  water;  add  3  pounds 
granulated  sugar  and  mix  thoroughly.  This  will  produce 
about  one  and  one  half  quarts  of  gum  tragacanth  stock. 
One  quart  of  this  stock  is  commonly  used  in  making  ten 
gallons  of  ice  cream. " 

Tragacanth  l  is  the  gummy  exudation  from  plants  be- 
longing to  the  genus  Astragalus,  family  Leguminosae.  The 
gum  is  in  ribbon-shaped  bands,  i  to  3  mm.  thick,  long  and 
linear,  straight  or  spirally  twisted. 

"  Indian  gum" 2  has  its  origin  in  other  plants  and  is 
usually  found  in  lumps,  never  in  ribbon-shaped  bands. 

Because  of  this  difference  in  physical  characteristics, 
adulteration  of  tragacanth  with  the  cheaper  Indian  gum 
is  probably  not  attempted.  But  large  quantities  of  gum 
are  sold  in  the  pulverized  form  in  which  no  physical  dif- 
ference can  be  detected.  It  has  been  found3  that  Indian 
gum  has  a  volatile  acidity  7^  times  as  great  as  that  of 
tragacanth.  Or  expressed  as  acetic  acid,  Indian  gum 
contains  about  15.8  per  cent  acetic  acid  and  tragacanth, 
2.1  per  cent  acetic  acid. 

1  U.  S.  Pharmacopoeia.          2  U.  S.  Dept.  of  Agr.,  Bui  Chem.  Cir.  94. 
3  U.  S.  Dept.  of  Agr.,  Bui.  Chem.  Cir.  94. 


PREPARING  THE  MIX.     FILLERS  AND   BINDERS       149 

Gelatin,  gum  tragacanth  and  other  binders  are  pre- 
pared with  sugar  and  sold  under  various  commercial 
names.  Powdered  arrow  root,  sago,  Iceland  moss,  gly- 
cerine, etc.,  are  occasionally  used  in  ice-cream  making, 
but  have  no  great  commercial  importance. 

Ice  cream  that  is  to  be  used  in  soda  water  must  con- 
tain sufficient  binder  to  prevent  it  from  being  broken  up 
and  dissolved  by  the  jet  of  soda.  Cream  made  especially 
for  fountain  use  frequently  is  of  lower  fat  content  and 
higher  gum  or  gelatin  content  than  the  product  made 
for  the  regular  trade. 

Most  ice-cream  manufacturers  use  some  one  of  the  many 
prepared  binders  or  fillers.  These  latter  are  usually  ob- 
tained in  powder  form.  A  certain  amount  of  this  powder 
is  thoroughly  mixed  with  the  dry  granulated  sugar.  Then 
some  cream  is  added  and  the  whole  stirred  to  form  a  thick 
paste.  By  first  mixing  the  sugar  and  filler  the  danger  of 
lumping  is  much  lessened.  More  cream  is  gradually 
added  to  the  sugary  paste  until  a  uniform  emulsion  is 
formed.  This  is  then  strained  into  the  definite  amount 
of  cream  to  be  frozen.  The  whole  is  thoroughly  mixed 
and  at  once  put  into  the  freezing  can.  About  five  and 
one-half  gallons  of  mix  make  ten  gallons  of  ice  cream. 

Great  care  should  be  taken  in  preparing  the  mix  not 
to  add  too  much  of  the  filler  and  binder  at  the  expense  of 
butter  fat.  Too  much  filler  or  binder  is  likely  to  cause 
a  sticky  and  soggy  body.  Such  ice  cream  is  more  like 
flavored  tough  pudding,  and  is  not  relished.  Ice  cream 
of  this  character  is  also  more  likely  to  coat  the  inside 
of  the  mouth  of  the  consumer  with  a  sticky  and  slimy 
layer. 


CHAPTER  XVII. 

FREEZING  THE  MIX. 

Ice  and  Salt.  —  Having  held  the  cream  at  about  34°  F., 
for  from  12  to  24  hours,  and  having  added  the  sugar, 
flavoring  and  binder,  we  are  ready  to  strain  and  freeze 
the  mixture. 

A  freezing  mixture  is  made  of  ice  and  salt.  The  chief 
cause  of  the  freezing  is  the  attraction  of  salt  for  water. 
This  causes  the  ice  to  melt  rapidly  and  absorb  heat. 
Whenever  a  frozen  solid  is  reduced  to  a  liquid,  heat  is 
absorbed,  and  when  one  pound  of  ice  melts  to  water  at 
32°  F.,  it  absorbs  144  British  Thermal  Units  (one  B.T.U. 
being  the  heat  given  up  by  i  pound  of  water  in  cooling 
i°  F.).  This  heat  is  absorbed,  to  a  great  extent,  from 
the  cream  mixture  in  the  freezing  can,  and  finally  the 
temperature  is  reduced  below  the  freezing  point. 

Cream  may  be  frozen  by  packing  the  mixture  of  ice 
and  salt  directly  around  the  freezing  can,  or  by  making  a 
brine  in  a  separate  receptacle  and  circulating  the  brine 
around  the  freezing  can. 

On  a  small  scale  the  tub  freezer  is  commonly  employed, 
and  the  ice  to  be  used  should  be  finely  crushed  in  order 
to  expose  to  the  salt  the  greatest  possible  amount  of  sur- 
face, and  insure  rapid  freezing.  When  large  chunks  are 
put  into  the  freezer,  they  do  not  pack  close,  large  air 
spaces  are  formed,  and  the  ice  can  not  so  well  perform  its 
function  of  extracting  the  heat  from  the  cream.  Further- 
more, large  pieces  of  ice  are  likely  to  jam  and  dent  the 

150 


FREEZING  THE   MIX  151 

freezing  can.     It  is  almost  impossible  to  pound  out  a 
dent  and  make  the  surface  as  smooth  as  it  was  originally. 

Ground  rock  salt  is  used  in  preference  to  the  fine  salt, 
because  the  former  can  be  mixed  more  uniformly  through 
the  crushed  ice,  and  does  not  dissolve  too  rapidly.  Fine 
salt  dissolves  almost  immediately,  causes  the  pieces  of 
ice  to  freeze  together  into  chunks,  and  does  not  form  so 
uniform  a  freezing  mixture  as  does  the  crushed  rock 
salt. 

One  part  of  salt  mixed  with  about  twelve  parts  of  ice 
will  freeze  the  cream  in  about  the  proper  length  of  time,  and 
give  general  satisfaction,  but  the  amount  must  be  varied  to 
suit  conditions.  The  maker  needs  to  use  his  judgment  in 
this  respect. 

Ice  and  salt  are  sometimes  mixed  on  the  floor  in  a  manner 
similar  to  that  of  mixing  feed,  but  this  practice  has  two 
objectionable  features:  first,  a  great  deal  of  the  ice  will 
melt  before  it  can  be  used,  thus  causing  a  needless  waste 
of  ice;  and  secondly,  just  as  great  a  quantity  of  salt  will 
be  put  into  the  bottom  of  the  tub  as  on  top,  thus  causing 
a  needless  waste  of  salt. 

There  is  little  or  no  necessity  for  putting  salt  into  the 
bottom  of  the  tub,  because  the  salt  above  is  being  washed 
down  by  the  melted  ice.  No  salt  need  be  added  until 
the  freezing  tub  has  been  half  filled  with  ice.  At  this 
point  a  portion  of  the  salt  should  be  added,  and  then  re- 
latively greater  proportions  added  as  the  tub  is  filled. 
Crushed  ice,  free  from  salt,  may  be  first  added,  then 
the  mixture  of  crushed  ice  and  salt.  In  this  manner  the 
ice  and  salt  may  be  mixed  together  in  a  box  or  on  the  floor. 

The  chief  objection  to  the  use  of  too  much  salt,  aside 
from  the  needless  expense,  is  that  an  excess  of  salt  causes 
the  cream  to  freeze  too  rapidly,  This  rapid  freezing  is 


152  DAIRY  TECHNOLOGY 

likely  to  cause  a  grainy  texture  and  a  low  overrun.  A 
lack  of  sufficient  salt  causes  smeary  ice  cream.  Lumps  of 
butter  are  also  likely  to  form. 

In  the  winter,  when  the  freezer  is  in  a  very  cold  room, 
it  is  sometimes  noticed  that  an  unusually  long  time  is 
required  to  freeze  the  cream.  This  is  undoubtedly  due  to 
the  low  surrounding  temperature  retarding  the  melting 
of  the  ice.  When  the  melting  is  delayed,  the  absorption 
of  heat  from  the  cream  is  delayed  and,  therefore,  the 
freezing  process  is  retarded.  In  the  cold  room  the  ice 
around  the  freezer  does  not  melt  and  form  brine  rapidly; 
hence,  heat  can  be  conducted  from  the  cream  only  at 
points  where  the  ice  particles  are  against  the  can,  and 
this  is  but  a  relatively  small  proportion  of  the  entire  area 
of  the  can.  When  brine  is  formed,  it  is  in  contact  with 
the  entire  surface  of  the  freezing  can,  and  hence  conducts 
the  heat  from  the  cream  more  rapidly. 

To  overcome  this  slow  formation  of  brine,  it  is  recom- 
mended that  some  water  be  poured  over  the  ice  and  salt 
mixture.  Having  the  ice  crushed  into  very  fine  pieces 
will  also  aid  in  overcoming  this  difficulty. 

In  the  style  of  freezers  in  which  the  brine  system  is 
employed,  the  same  general  principles  apply.  The  mix- 
ture of  ice  and  salt  must  be  in  the  proper  proportion  to 
produce  a  brine  of  such  temperature  that  the  cream  will 
be  frozen  in  the  proper  length  of  time  to  insure  good  qual- 
ity of  ice  cream.  Under  average  conditions  a  mixture  of 
one  part  of  salt  to  fifteen  of  ice  will  produce  a  brine  of 
about  10°  F.,  and  will  do  satisfactory  work  in  the  freezer. 
Many  brine  freezers  are  provided  with  a  compartment  for 
this  purpose,  and  the  brine  circulated  by  means  of  a  pump 
driven  by  the  shaft  that  drives  the  freezer.  Factories 
equipped  with  artificial  refrigeration  commonly  have  a  large, 


FREEZING  THE   MIX  153 

well-insulated  tank,  and  the  brine  is  kept  cold  by  a  coil  of 
ammonia  pipes. 

Speed  of  Dasher.  —  The  speed  of  the  dasher  must  be 
such  that  the  cream  will  be  uniformly  frozen,  and  be  well 
whipped  during  the  freezing  process.  If  the  cream  is  put 
into  the  freezer  at  a  temperature  under  40°  F.,  it  will  be 
quickly  frozen,  and  the  freezer  should  be  run  at  its  maximum 
speed  during  the  entire  time.  If  the  temperature  of  the 
cream  is  50°  F.  or  above,  in  order  to  avoid  churning,  the 
freezer  should  be  run  at  slow  speed  at  first,  until  the  mix 
is  brought  down  close  to  the  freezing  point;  then  the 
machine  can  be  brought  to  full  speed  and  the  freezing 
completed.  If  it  is  impossible  to  run  the  freezer  at  low 
speed,  then,  intermittent  freezing  may  be  practiced.  If 
this  latter  is  resorted  to,  no  salt  should  be  added,  at  first,  to 
the  ice  around  the  freezing  can.  The  mixing  of  salt  would 
cause  the  can  to  freeze  fast,  and  the  part  of  the  cream  next 
to  the  can  would  freeze  solid,  thus  forming  icy  cream. 

In  the  vertical  batch  freezers,  the  dasher  commonly 
makes  90  to  100  revolutions  per  minute,  and  the  can,  re- 
volving in  the  opposite  direction,  makes  the  same  number 
of  revolutions,  the  result  being  equivalent  to  from  180  to 
200  revolutions  per  minute. 

Freezing  Period.  —  The  time  required  for  freezing  is 
dependent  upon  (i)  the  temperature  of  the  mix  when  put 
into  the  freezer,  (2)  the  freezing  mixture  (size  of  pieces 
of  ice  and  proportion  of  salt),  and  (3),  to  a  limited  extent, 
the  composition  of  the  mix.  The  composition  and  spe- 
cific gravity  of  the  mix  are  nearly  constant  for  the  same 
class  of  product,  so  that  the  maker  must  depend  upon 
regulating  the  two  other  factors  to  control  the  duration  of 
the  freezing  period.  This  latter  cannot  be  varied  widely 
without  impairing  the  texture  of  the  product. 


154  DAIRY  TECHNOLOGY 

A  prolonged  freezing  period  may  be  due  to  (i)  insuffi- 
cient salt,  (2)  coarse  ice,  and  (3)  warm  mix.  The  result 
may  be  a  greasy  ice  cream,  perhaps  containing  granules 
of  butter;  this  latter  is  very  objectionable  to  the  con- 
sumer. 

Rapid  freezing  of  the  cream  is  due  chiefly  to  an  excess 
of  salt,  or  to  very  finely  crushed  ice,  well  packed  around 
the  can. 

The  result  of  too  rapid  freezing  is  a  coarse,  granular 
texture,  the  ice  cream  frequently  containing  small  crys- 
tals of  clear  ice. 

When  cream  is  put  into  the  freezer  at  a  temperature 
of  40°  F.,  or  less,  the  proper  texture  and  swell  will  be 
secured  by  allowing  10  to  14  minutes  for  the  freezing  proc- 
ess. If  the  cream  is  15°  to  20°  F.  warmer  than  this,  an 
additional  five  minutes  should  be  allowed  for  the  freezing. 
When  cream,  at  60°  F.,  is  frozen  in  eight  minutes,  it  passes 
through  the  whipping  stage  so  quickly  that  insufficient 
swell  will  be  obtained,  and  the  texture  is  likely  to  be  coarse 
and  granular. 

Freezing  Point.  —  The  freezing  point  of  ice  cream, 
as  commonly  made  commercially,  is  not  a  very  variable 
factor;  but  when  fruit  ice  cream  and  the  various  ices  are 
made,  the  addition  of  the  fruit  and  the  extra  sugar  re- 
quired lowers  the  freezing  point.  The  freezing  point  of 
sherbets,  water  ices  etc.,  is  5°  to  8°  lower  than  that  of 
ice  cream.  A  little  colder  freezing  mixture  and  a  lower 
storing  temperature  are  necessary  for  these  products. 

The  freezing  point  of  the  cream  is  not  affected,  mate- 
rially, by  the  fat  content,  nor  by  the  presence  of  fillers  or 
binders;  but  all  of  these  make  the  cream  appear  more  firm 
at  a  given  temperature  than  cream  in  which  these  things 
are  lacking. 


FREEZING  THE   MIX  155 

Effect  of  the  Sugar  Content  on  the  Freezing  Point.1  - 

"  Sugar  goes  into  true  solution  and  has  a  low  molecular 
weight  as  compared  to  egg  or  gelatine.  It  lowers  the 
freezing  point  very  materially,  and  uniformly,  in  pro- 
portion to  its  presence.  Similarly  the  milk  sugar,  a  nor- 
mal milk  constituent,  being  in  true  solution,  causes  milk 
to  freeze  at  a  lower  temperature  than  does  pure  water. 
Ice  cream  sweetened  to  average  taste  contains  approxi- 
mately 14  per  cent  added  sugar,  and  has  a  freezing  point 
of  about  28^°  F.  When  ice  cream  has  frozen  to  the  proper 
consistency  for  removing  from  the  freezer  to  the  packers, 
its  temperature  is  about  28°  to  27°  F.  The  following 
table,  prepared  from  the  data  obtained  at  this  station, 
using  a  Beckmann's  freezing-point  thermometer  graduated 
in  T^Q  of  a  degree,  may  be  of  interest  as  showing  the 
freezing  points  of  different  sugar  solutions. 


Material. 

Observed 

freezing  point. 

Plain  skim  milk  

31  03°F. 

5  per  cent  solution  sugar  in  skim  milk  

30  40°  F. 

10  per  cent  solution  sugar  in  skim  milk  
14  per  cent  solution  sugar  in  skim  milk  

29.7o°F. 
28  60°  F. 

25  per  cent  solution  sugar  in  skim  milk  

27    07°F.  " 

Swell.  —  The  volume  of  ice  cream  obtained  in  excess  of 
the  amount  of  total  mix  put  into  the  freezer  constitutes 
the  "  swell "  or  overrun.  This  increase  in  volume  is  due 
almost  wholly  to  the  incorporation  of  air  into  the  product 
and,  therefore,  can  scarcely  be  called  an  overrun.  Noth- 
ing of  a  tangible  character  is  added  during  the  freezing 
process. 

The  /more  viscous  the  cream  is,  the  greater  the  swell 
that  may  be  secured,  because  the  viscous  cream  is  able 
to  retain  the  air  that  is  beaten  into  it. 

The  amount  of  swell  is  influenced  by  the  rate  of  freezing. 
1  Vermont  Bui.  No.  155. 


156  DAIRY  TECHNOLOGY 

When  cream  is  frozen  very  quickly,  less  swell  is  secured. 
The  reason  for  this  seems  to  be  that  the  swell  is  produced 
only  while  the  cream  is  passing  through  a  few  degrees  of 
temperature  just  before  it  freezes.  Only  during  this  short 
time  is  it  sufficiently  viscous  to  retain  the  air  that  is  beaten 
into  it.  According  to  Washburn,1  when  the  temperature 
of  the  cream  reaches  34°  F.,  the  cream  begins  to  foam  up 
and  continues  to  increase  in  volume  until  a  temperature 
of  29°  or  28°  F.  is  reached.  At  this  point  the  temperature 
remains  constant  for  from  four  to  fifteen  minutes.  During 
this  time  the  latent  heat  is  being  extracted  from  the  cream 
by  the  freezing  mixture.  The  swelling  of  the  cream,  that 
begins  at  about  34°  F.,  is  most  rapid  toward  the  end  of 
this  period  of  lowering  temperature.  Just  before  the  cream 
freezes,  the  swell  is  very  rapid. 

The  effect  upon  the  swell,  of  over-freezing,  is  reported 
by  the  same  authority.  A  series  of  trials  was  made  in  a 
double-disc  continuous  freezer,  run  at  the  rate  of  225 
revolutions  per  minute.  It  was  found  that  when  the  ice 
cream  was  drawn  off  at  a  temperature  of  29°  F.,  the  swell 
was  70  per  cent;  at  28°  F.,  60  per  cent;  at  27°  F.,  50  per 
cent;  at  26°  F.,  43  per  cent;  at  25°  F.,  40  per  cent.  The 
ice  cream  drawn  off  at  29°  F.  was  too  soft,  but  that  at  28° 
was  entirely  satisfactory. 

The  speed  of  the  rotator  or  beater  also  influences  the 
overrun  or  swell.  Some  freezers  have  facilities  for  varying 
the  speed,  making  it  slow  at  first,  then  during  the  latter 
part  of  the  freezing  period  increasing  the  speed.  The 
higher  the  speed  up  to  a  certain  limit  (250  rev.  per  min.), 
the  more  air  is  beaten  into  the  ice  cream.  High  speed 
during  the  first  part  of  the  freezing  period  may  cause  the 
cream  to  churn. 

1  Vermont  Bui.  155. 


FREEZING  THE  MIX  157 

Stopping  Point.  —  When  frozen  to  the  consistency  of 
thick  syrup  the  ice  cream  is  dipped  or  poured  out  into  pack- 
ing cans,  which  have  been  previously  iced.  Care  should 
be  exercised  in  the  transfer  to  avoid  expelling  the  in- 
corporated air.  When  the  ice  cream  is  put  into  packing 
cans  that  are  not  standing  in  ice,  the  relatively  warm  can 
melts  some  of  the  cream.  This,  when  refrozen,  is  coarse 
and  icy.  Where  hardening  rooms  are  used,  this  is  avoided 
by  placing  the  packing  cans  in  the  hardening  room  for  a 
while  before  filling.  Twelve  to  twenty-four  hours  after 
being  frozen  the  ice  cream  will  be  found  to  have  a  better 
and  more  uniform  flavor  because  of  the  blending  of  the 
several  flavors  into  one. 

Hardening.  —  To  prepare  ice  cream  for  delivery,  it 
must  be  thoroughly  hardened.  This  can  be  accomplished 
only  by  lowering  the  temperature  of  the  product  to  from 
14°  to  17°  F.  The  hardening  may  be  done  in  the  packing 
tubs  that  are  used  for  delivery,  setting  the  cans  of  ice 
cream  in  a  tank  of  brine  or  in  a  room  cooled  by  artificial 
refrigeration. 

Just  before  being  sent  from  the  factory,  the  ice  cream 
must  be  re-iced.  The  space  around  the  can  should  be  well 
filled,  and  the  top  well  covered  with  the  ice  and  salt  mix- 
ture before  the  ice  cream  is  shipped.  Some  manufacturers 
cover  the  can  and  tub  with  a  blanket  and  finally  with  a 
neatly  fitting  oil  cloth. 

Returned  Goods. —  It  is  a  good  rule  never  to  allow 
melted  ice  cream  to  be  returned  to  the  factory;  but  at 
times  Irhis  cannot  be  avoided.  A  total  loss  may  be  pre- 
vented by  churning  such  melted  ice  cream.  Butter  made 
from  such  cream  makes  satisfactory  cooking  butter.  The 
melted  ice  cream  should  be  mixed  with  skim  milk  and  re- 
skimmed  on  a  separator;  a  starter  should  then  be  added  to 
the  cream  and  the  whole  ripened  and  then  churned  as  usual. 


158  DAIRY  TECHNOLOGY 

If  the  melted  cream  is  of  good  flavor  and  fresh,  it  may 
be  refrozen. 

Fancy  Ice  Cream.  —  The  most  common  of  the  fancy  ice 
cream  is  brick,  made  up  of  several  layers.  These  bricks  are 
usually  made  up  of  three  differently  colored  layers.  Red, 
white  and  chocolate  are  common  colors.  The  molds  are 
of  various  sizes,  such  as  one  pint,  one  quart,  etc.  The  molds 
are  also  of  two  kinds,  those  having  a  loose  cover,  both  on 
top  and  bottom,  and  those  having  only  the  top  cover  loose. 

Small  or  individual  molds  are  also  manufactured  rep- 
resenting fruits,  animals,  soldiers,  etc.  Ice-cream  molds 
of  this  kind  are  in  demand  especially  for  children's  parties. 
If  cream  is  colored  in  this  connection  it  should  imitate  as 
nearly  as  possible  the  object  it  is  supposed  to  represent. 

To  make  the  layer  ice  cream,  about  one-third  of  the 
mold  is  filled,  say,  with  white  ice  cream.  This  is  smoothed 
on  the  surface,  then  another  third  of  the  mold  is  filled  with 
chocolate  or  dark-colored  ice  cream.  This  is  smoothed  off, 
and  finally  the  last  third  of  the  mold  is  filled  with  the  red 
ice  cream.  This  is  leveled  off  even  with  the  top  edge  of  the 
mold  and  the  cover  put  on.  Sometimes  a  sheet  of  paraffined 
paper  is  laid  on  the  top  of  the  ice  cream  before  the  cover 
is  put  on.  This  is  perhaps  most  desirable  when  the  mold 
is  old  and  loose  around  the  edge. 

When  the  mold  is  filled  and  the  cover  is  on,  tie  string 
around  the  mold  to  hold  the  cover  tight. 

Place  the  mold  at  once  in  a  freezing  temperature.  This 
maybe  on  shelves  in  a  hardening  room,  or  in  a  mixture  of 
crushed  ice  and  salt.  If  the  latter,  the  mixture  should 
rest  on  a  perforated  board  to  allow  the  brine  to  drain 
through  into  a  lower  jacket.  The  brine  is  cold  and  should 
be  retained  in  the  cooling  tank  or  box.  The  box  should 
be  provided  with  a  cover. 


FREEZING  THE   MIX  159 

Allow  the  molds  to  remain  here  long  enough  to  freeze 
solid.  The  hard  frozen  ice  cream  can  be  removed  from 
the  mold  by  dipping  the  mold  and  contents  into  cold  water, 
and  by  wiping  the  mold  on  the  outside  with  a  dry  towel. 
The  ice  cream  may  also  be  loosened  from  the  mold  by  using 
a  case  knife  around  the  edges. 

Fat  Content  of  Different  Portions.  —  Some  ice-cream 
dealers  claim  that  ice  cream  which  has  stood  in  a  packer 
for  a  week  shows  a  differently  distributed  fat  content  than 
at  the  beginning  of  the  week.  This  observed  difference 
in  the  fat  content  in  the  different  parts  of  the  ice  cream  is 
evidently  due  to  the  rising  of  the  fat,  through  the  partially 
melted  ice  cream,  and  in  some  cases  to  the  alternate  freez- 
ing and  thawing,  crowding  a  large  per  -cent  of  the  solids 
toward  the  center. 

Washburn1  has  found  that  the  fat  in  semi-melted  ice 
cream  rises  somewhat.  He  tested  portions  of  a  can  of  ice 
cream  that  had  stood  for  one  week  in  a  mellow  condition, 
and  found  that  the  top  portion  of  cream  contained  28  per 
cent  fat,  the  middle  15  per  cent  and  the  bottom  five  per 
cent.  The  same  authority  states  that  gelatine  and  gum 
tragacanth  had  but  little  effect  in  preventing  this  rise  of 
fat.  Fruit  ice  creams  separated  more  quickly  than  the 
plain  flavors,  due  to  the  heavy  fruit  and  rich  syrup. 
However,  when  the  cream  was  properly  hardened,  and 
held  in  that  condition,  the  fat  content  of  the  different 
parts  did  not  change. 

1  Vermont  Bui.  155. 


CHAPTER  XVIII. 

FORMULAS. 

Vanilla  Ice  Cream.  —  Formulas  for  ice  cream  may  be 
obtained  from  various  sources,  and  are  of  infinitely  great 
variety.  A  standard  vanilla  ice  cream  that  gives  general 
satisfaction  is  made  as  follows: 

45  pounds  i8-per-cent  cream. 
8  pounds  sugar. 
4  ounces  vanilla  extract. 
4  ounces  gelatine. 

This  will  make  ten  gallons  of  ice  cream  testing  15.1 
per  cent  fat.  One  of  the  commercially  sold  fillers  may  be 
substituted  for  the  gelatine.  These  should  be  used  accord- 
ing to  directions  and  according  to  body  desired  in  the  ice 
cream. 

This  vanilla  ice  cream  may  be  used  as  a  stock  cream  for 
making  small  batches  of  other  flavors.  For  instance,  if 
a  small  quantity  of  chocolate  ice  cream  is  desired,  it  can 
be  made  by  taking  out  the  required  amount  of  vanilla  ice 
cream  (mix)  and  adding  the  chocolate  syrup  to  it. 

Nut  ice  creams  are  commonly  made  by  exactly  the 
same  formula  as  the  vanilla,  except  for  the  addition  of 
nuts.  The  nuts  should  not  be  added  until  the  cream  is 
partly  frozen.  This  prevents  settling  of  the  added  nuts. 

Any  ice  cream  in  which  a  syrup  or  liquid  flavoring  is 
used  may  be  made  from  the  above  formula,  but,  in  some 
instances,  more  sugar  will  be  necessary  and  the  vanilla 
will  be  omitted. 

160 


FORMULAS  l6l 

Fruit  Ice  Cream.  —  Nothing  is  more  justly  popular  than 
fruit  ice  cream  in  which  the  fresh  fruit  is  used  —  especially 
strawberry  or  peach.  To  make  10  gallons  of  strawberry 
ice  cream: 

45  pounds  i8-per-cent  cream. 
8  pounds  sugar. 

i  gallon  crushed  strawberries  (sweetened). 
4  ounces  gelatine. 

In  adding  fruit  of  any  kind  to  any  mixture  containing 
milk  and  cream  it  is  usually  best  to  add  it  after  the  cream 
has  been  partly  frozen.  If  added  sooner  the  heavier 
fruit  is  likely  to  settle,  and  the  acid  in  the  juice  is  likely 
to  cause  some  coagulation. 

PARFAIT.1 

4  gallons  30-per-cent  cream. 

Yolks  of  10  dozen  eggs  (stirred  and  beaten). 

14  pounds  sugar. 

4  ounces  vanilla  extract. 

4  pounds  ground  walnut  meats  (or  other  nuts). 

MOUSSE.  1 

2  gallons  3O-per-cent  cream  (whipped). 
4  pounds  sugar. 

1  quart  cranberry  juice  (or  other  fruit  or  nuts). 
J  pints  lemon  juice. 

LACTO.2 

6  gallons  sour  skim  milk  or  buttermilk. 
1 8  pounds  sugar. 

2  dozen  eggs  (yolks  and  whites  beaten  separately) 

2  quarts  cherry  juice  or  cherry  syrup  (or  other  fruit). 

3  pints  lemon  juice. 

1  Iowa  Bui.  123.  2  Iowa  Bui.  118. 


1 62          DAIRY  TECHNOLOGY 

SHERBET. 

6  gallons  water  or  milk. 

6  quarts  orange  juice  (or  other  fruit). 

1  pint  lemon  juice. 

2  dozen  eggs,  whites  only. 
23  pounds  sugar. 

Another  recipe  for  a  very  delicious  and  rich  sherbet, 
especially  useful  when  made  on  a  small  scale,  is  as  follows: 

i  quart  of  water. 

i  pound  of  sugar. 

i  quart  of  fresh  strawberries. 

Whites  of  six  eggs. 

Juice  of  two  lemons. 

Boil  sugar  and  water  together  to  make  the  syrup.  Pick 
over  the  strawberries  and  thoroughly  mash  them;  then 
add  the  lemon  juice  and  mix.  When  the  syrup  has  been 
cooled,  pour  it  over  the  mashed  berries,  mix  and  strain 
into  the  freezing  can,  and  freeze.  When  about  half  frozen 
add  the  beaten  whites  of  eggs  and  complete  freezing. 


CHAPTER  XIX. 

ICE-CREAM  MACHINERY. 

THE  great  growth  of  the  ice  cream  industry  has  naturally 
been  accompanied  and  aided  by  the  invention  of  various 


FIG.  33.  —  Davis  milk-can  drip  saver. 

pieces  of  machinery  especially  adapted  to  the  needs  of 
the  ice-cream  maker. 

163 


164 


DAIRY  TECHNOLOGY 


For  the  storage  or  holding  of  cream  the  small  factory 
may  employ  common  milk  cans,  but  in  the  large  factory, 
vats  are  necessary,  and  these  may  be  ordinary  jacketed 
tin  vats  or  enameled  iron  tanks.  The  last  mentioned  are 
perfectly  sanitary  and  easily  cleaned,  being  lined  with  a 
thin  coating  of  enamel,  perfectly  smooth  and  without  a 


FIG.  34.  —  Sweet  cream  storage  rooms.     (Ice  Cream  Trade  Journal.) 

seam  or  crack.  A  vat  having  cooling  facilities  attached 
is  preferred,  unless  it  be  placed  in  a  refrigerator  room. 

When  pasteurization  is  practiced,  the  machines  used 
are  the  same  as  those  made  for  use  in  the  creamery  or 
city  milk  plant. 

The  ice-cream  mixer  is  used,  when  large  quantities  of 
material  are  handled  at  one  time,  to  secure  a  perfectly 
uniform  mix.  This  machine  is  invariably  a  cooler  as 
well  as  a  mixer.  One  general  style  having  a  horizontal 


ICE-CREAM  MACHINERY 


stirring  device  through  which  ice  water  or  cold  brine 
may  be  pumped,  resembles  many  styles  of  cream  ripeners 
commonly  used  in  butter  factories.  Another  style  is  the 
vertical  mixer,  having  an  upright  dasher  for  a  stirring  device 
and  a  jacket  for  the  circulation  of  ice  water.  This  is  similar 
in  general  make  up  to  the  starter  can  of  the  butter  factory. 

Freezers.  —  Ice-cream  freezers  are  of  many  styles  and 
designs,  but  may  be  classified  under  the  following  heads: 

i.  Batch  Ice-cream  Freezer 
or  Tub  Freezer,  in  which  the 
freezing  can  is  set  into  a  wooden 
tub  and  the  ice  and  salt  packed 
around  it.  This  is  the  old  style 
freezer,  the  simplest  and  most 
primitive  in  construction  and 
mechanism.  Of  this  style  are 
the  small  household  freezers 
and  also  many  power  machines 
used  in  small  factories.  There 
are  probably  more  freezers  of 
this  kind  in  use  than  all  other 
kinds  together.  However,  they 
are  not  adaptable  to  ice-cream 
making  on  a  large  scale ;  hence, 
in  the  large  factory,  machines 
of  a  more  improved  design  are 
usually  employed.  The  gear  wheels  of  the  power  tub 
freezers  are  so  arranged  that  the  can  is  revolved  in  one 
direction  and  the  dasher  in  the  opposite  direction  at  the 
same  speed.  In  many  of  the  hand  freezers  the  dasher  is 
stationary,  and  the  can  is  not  geared  high,  so  it  is  difficult 
to  attain  sufficient  speed  on  the  crank  to  properly  beat  the 
cream  during  freezing. 


FIG.  35.  —  The  Little  Giant 
ice-cream  freezer. 


l66  DAIRY  TECHNOLOGY 


FIG.  36.  —  The  Miller  horizontal  ice-cream  freezer. 


FIG.  37.  —  C.  P.  disc  ice-cream  freezer. 


ICE-CREAM   MACHINERY 


I67 


2.  The  Batch  Brine  Freezer  is  of  two  varieties,  the  ver- 
tical and  the  horizontal.  In  these  freezers  instead  of 
packing  ice  around  the  freezing  can,  brine  is  made  in 
a  separate  compartment  and  pumped  through  a  jacket 


FIG.  38.  —  Improved  Model  D  brine  freezer. 

surrounding  the  freezing  can,  circulating  from  end  to  end 
in  order  to  freeze  uniformly.     The  batch  freezers  are  used 
in  freezing  products  in  which  fruits  of  various  kinds  and 
beaten  eggs  are  added  after  the  mix  is  partly  frozen. 
3.   The  Continuous  Brine  Freezer  is  a  machine  permitting 


168  DAIRY  TECHNOLOGY 

the  unfrozen  mix  to  enter  continuously  at  one  end  and  the 
frozen  product  continuously  to  run  out  at  the  other  end. 
A  common  form  of  these  continuous  freezers  is  the  disk 
freezer  consisting  of  two  oblong  tanks,  side  by  side.  In 
each  tank  are  several  revolving,  hollow  disks  on  a  hollow 
shaft  through  which  the  brine  for  freezing  is  pumped. 

The  cream  flows  into  the  first  tank  or  freezing  compart- 
ment from  the  supply  reservoir  on  to  the  revolving  disks 


FIG.  39.  —  The  Creasy  ice  breaker. 

and  the  freezing  process  begins.  At  the  far  end  of  this 
tank  the  partly  frozen  mixture  overflows  into  the  second 
compartment  and  passes  along  over  the  freezing  disks. 
(The  smaller  freezers  have  but  one  compartment.)  In 
this  compartment,  just  above  the  disks,  is  a  screw  that 
carries  away  the  frozen  cream  and  discharges  it  into  the 
packing  cans.  The  top  of  each  freezing  compartment  is 
provided  with  a  plate-glass  cover,  so  that  the  cream  is  in 
view  during  the  entire  freezing  process. 


ICE-CREAM   MACHINERY 


169 


Ice  Crusher.  —  This  is  a  great  labor-saving  device  and 
is  indispensable  where  large  quantities  of  ice  are  crushed. 
The  machine  breaks  the  ice  into  pieces  of  a  more  uniformly 
small  size  than  can  possibly  be  done  by  hand  with  an  ax  or 
stomper. 

Homogenizer.  —  This  is  one  of  the  latest  inventions  in 
ice-cream  machinery.  As  its  name  indicates,  it  is  a  ma- 


FIG.  40.  —  A  six-cylinder  Progress  homogenizer. 

chine  for  converting  liquids  such  as  cream  into  a  homo- 
geneous mass.  This  is  accomplished  by  breaking  the  fat 
globules  into  such  fine  particles  that  they  are  unable  to 
rise  to  the  surface,  but  remain  incorporated  in  the  liquid. 
The  machine  consists  of  a  pump  or  a  series  of  pumps  which 
discharge  the  liquid  against  the  homogenizing  valve. 
This  latter  may  be  compared  to  a  safety  valve  which  blows 
off  at  a  pressure  of  from  2000  to  3000  pounds  per  square 
inch.  The  valve  disk  is  made  of  agate  and  closes  per- 


DAIRY  TECHNOLOGY 


fectly  into  the  seat.  When  the  pressure  from  the  pump 
is  sufficient,  the  valve  is  forced  open,  but  the  space  be- 
tween the  disk  and  the  seat  is  so  small  that  when  the  fat 


FIG.  41 .  —  The  Honey  cone  machine. 

globules  are  forced  through  they  are  separated  into  tiny 
particles. 

The  homogenizer  is  and  has  been  used  for  manufacturing 
cream  from  skim  milk  and  butter.  Some  have  even  gone 
so  far  as  to  make  the  skim  milk  from  milk  powder  and  mixed 
it  with  unsalted  storage  or  fresh  butter.  Finished  prod- 
ucts made  and  offered  for  sale  in  this  manner  must  be 


ICE-CREAM   MACHINERY  171 

labeled  as  such.  This  process  makes  the  problem  of  getting 
sweet  cream  less  difficult. 

Sanitary  Pipes  and  Fittings.  —  The  only  kind  of  pipes 
that  should  be  used  for  transmitting  cream  and  milk  are 
the  so-called  sanitary  pipes.  The  piping  is  perfectly  smooth 
and  heavily  tinned.  It  is  in  short  lengths  and  put  together 
in  a  manner  similar  to  that  of  connecting  fire  hose,  so  that 
the  pipes  may  all  be  taken  apart  and  cleaned  very  readily. 

Ice-cream  Can  Washer.  —  This  machine  finds  a  place  in 
large  factories  where  a  great  many  packing  cans  are  used. 

I 


FIG.  42.  —  Fort  Atkinson  ice-cream  can  washer. 

It  is  a  contrivance  in  which  brushes  and  jets  of  water  and 
steam  are  used  to  cleanse  and  sterilize  the  cans  in  much  the 
same  way  that  bottles  and  cans  are  cleaned  and  sterilized 
in  a  city  milk  plant. 

Packing  Cans.  —  These  are  of  great  importance  from  a 
sanitary  standpoint,  because  the  ice  cream  remains  in 
them  often  for  several  days.  There  should  be  no  crevices 
or  rough  spots  in  the  can  and  no  exposed  iron.  Heavily 
tinned  cans  are  extensively  used,  but  enameled  iron  ones 
are  better,  being  smoother,  more  easily  and  perfectly 
cleaned  and  hence  more  sanitary. 


172  DAIRY  TECHNOLOGY 

Sterilizer.  —  A  large  steam  sterilizer  is  essential  for  a 
factory  turning  out  a.  strictly  sanitary  product.  Here  all 
the  freezing  and  packing  cans  and  utensils  used  in  handling 
the  materials  can  be  made  perfectly  sterile  daily. 

Many  small  utensils  too  numerous  to  mention  are  needed 
in  the  ice-cream  factory. 


CHAPTER  XX. 
ICE-CREAM  FACTORIES. 

Local  Creameries.  —  The  farmers'  co-operative  cream- 
ery of  to-day  is  in  keen  competition  with  private  enter- 
prises that  as  a  rule  have  a  much  larger  working  fund  than 
the  local  creameries.  These  private  enterprises  are  usually 
managed  by  better  business  methods,  are  better  located 


FIG.  43.  —  View  of  Collins  Bros.'  ice-cream  freezing  room. 
(Ice  Cream  Trade  Journal.) 

in  relation  to  the  markets,  and,  in  most  cases,  are  doing 
business  on  a  larger  scale  than  the  local  creamery  plant. 
It  therefore  behooves  the  local  creamery  to  adopt  modern 
business  methods,  to  cater  to  the  markets  and  to  find  the 
most  profitable  method  of  disposing  of  their  products. 

173 


174  DAIRY  TECHNOLOGY 

The  farmers'  local  creameries,  on  the  other  hand,  have 
the  advantages  of  having  easier  access  to  a  large  supply  of 
fresh  sweet  cream  at  a  minimum  cost.  These  local  cream- 
eries have  the  building  and  much  of  the  costly  machinery, 
such  as  engine,  boiler,  vats,  etc.,  the  initial  expense  of  which 
does  not  need  to  be  charged  up  against  the  ice-cream 
department.  They  also  sustain  a  minimum  loss  on  any 
surplus  cream.  In  case  that  the  ice-cream  consumption 
is  diminished,  as  is  usually  the  case  during  cold  weather, 
large  city  ice-cream  manufacturers  often  lose  money  on 
their  sweet  cream.  The  creamery  can  turn  this  surplus 
cream  into  butter  with  scarcely  any  loss. 

Since  the  price  of  butter  is  always  low  in  summer,  at 
the  time  when  production  is  greatest,  any  method  of  con- 
verting the  raw  material  at  this  time  into  a  higher  priced 
product  would  seem  to  be  worthy  of  our  consideration. 
The  manufacture  of  ice  cream  has  been  tried  and  proven 
successful  in  the  creamery. 

Advantages.  —  The  chief  advantages  of  ice-cream  making 
as  a  side  line  in  local  creameries  are  as  follows: 

1.  The  profits  from  this  product  are  materially  greater 
than  those  obtainable  from  butter  during  the  summer. 

2.  The  creamery  is  already  equipped  with  steam,  ice, 
power  and  a  suitable  building  for  the  manufacture  of  ice 
cream. 

3.  The  local  creamery  is  in  a  position  to  secure  fresh 
sweet  cream  direct  from  the  producer. 

4.  The  local  creamery  can  supply  its  own  and  neighbor- 
ing towns  with  this  product  with  greater  ease  and  efficiency 
than  can  a  large  factory  in  a  distant  city. 

As  in  starting  any  new  line  of  business,  it  must  be  taken 
up  on  a  small  scale  to  begin  with.  A  suitable  market  must 
be  found  for  the  product.  Some  creameries  are  so  located 


ICE-CREAM   FACTORIES  175 

that  they  could  not  profitably  take  up  this  side  line,  but 
such  conditions  are  rarely  found.  In  many  small  towns 
ice  cream  is  a  rare  delicacy,  but  when  it  is  easily  available 
the  people  soon  acquire  the  ice-cream  habit  and  consume 
large  quantities  of  it,  thus  increasing  the  demand. 

Cost  of  Equipment.  —  The  machinery  for  making  ice 
cream  on  a  small  scale  need  not  be  extensive  or  costly. 
Just  as  good  a  product  can  be  made  in  the  simple  tub 
freezer  as  can.be  made  in  the  most  complex  freezer  on 
the  market. 

The  machinery  absolutely  necessary  for  the  manu- 
facture of  60  to  500  gallons  of  ice  cream  per  week  would 
cost  about  as  follows: 

i  io-gal.  tub  freezer $80.00  to  $110.00 

i  ice  crusher i .  50  to  50 .  oo 

1  pulley  and  24  ft.  of  4-in.  belting 10.00  to  20.00 

4  to  40  large  packers  or  8  to  80  small  ones ...  30 .  oo  to  400 .  oo 

2  to  20  io-gal.  cream  cans  or  a  vat 4. 50  to  50.00 

Ice  tools,  ice-cream  utensils,  etc 10 .  oo  to  20 .  oo 


Total $136 .  oo  to    $650 .  oo 

One  hundred  and  fifty  dollars  will  buy  the  necessary 
equipment  for  a  creamery  that  is  starting  the  manufacture 
of  ice  cream  in  a  locality  where  the  demand  is  small. 

Profits  from  this  Product.  —  The  cost  of  making  one 
gallon  of  ice  cream  may  be  calculated  as  follows:  The 
creamery  buys  fat  in  sweet  cream  at  3  cents  above  the 
market  quotation  for  butter.  Let  us  assume  that  the 
average  quotation  during  the  summer  is  25  cents  per 
pound. 

Cents. 
4.7  Ibs.  i8-per-cent  cream  at  28  cents  per  pound  of  fat ....      23 . 7 

T\J-  Ib.  sugar 6.0 

Flavoring  and  binder i .  o 

Ice  and  labor 3.3 

34-o 


176  DAIRY  TECHNOLOGY 

This  ice  cream  that  costs  34  cents  per  gallon  to  make, 
sells  at  80  cents  per  gallon.  The  fat  content  of  the  above 
gallon  of  ice  cream  is  .846  pound.  The  materials  other 
than  the  cream  cost  10.3  cents;  hence  69.7  cents  was 
received  for  the  .846  pound  of  fat,  or  82.4  cents  per  pound. 

This  pound  of  fat  would  have  made  about  i .  2  pounds  of 
butter  which,  at  25  cents  per  pound,  would  have  brought 
30  cents.  This  shows  a  difference  of  52.4  cents  per  pound 
of  fat  in  favor  of  ice-cream  making.  Making  allowance 
for  possible  losses  on  ice  cream,  this  product  should,  under 
favorable  conditions,  net  about  twice  as  much. per  pound 
of  fat  as  butter.  This  cost  will  vary  under  different  con- 
ditions. 

Many  local  creameries  have  made  ice  cream  during 
the  past  few  summers  and  have  made  a  success  of  this 
side  line;  they  have  been  able  to  pay  the  farmers  more 
for  their  cream  than  factories  not  making  ice  cream, 
and  they  have  been  better  able  to  compete  successfully 
with  large  private  enterprises. 

The  Large  City  Factory.  —  Under  the  above-described 
conditions,  ice  cream  can  be  made  with  a"  minimum  out- 
lay of  money.  The  amount  of  machinery  may  be  greatly 
increased  to  facilitate  the  handling  of  larger  quantities 
of  material.  In  some  of  the  big  ice-cream  factories  of 
the  cities  there  is  a  large  investment,  both  in  building  and 
equipments. 

Owing  to  difficulties  in  securing  an  ample  supply  of 
fresh  cream  most  large  factories  have  installed  homoge- 
nizers,  and,  especially  during  the  summer,  make  homoge- 
nized cream  from  butter  and  milk. 

Homogenized  Cream.  —  Milk  is  received  each  morning 
direct  from  the  farms.  Each  can  is  inspected  and,  if 
found  fresh  and  clean,  is  accepted  and  emptied  into  the 


ICE-CREAM   FACTORIES 


177 


receiving  vat.  From  here  it  runs  through  a  pasteurizer, 
then  over  a  cooler  which  brings  it  to  a  temperature  of 
34°  to  38°  F.,  thence  to  huge  holding  vats  in  a  refriger- 
ated room,  where  it  is  held  until  needed. 

In  another  cold  room  is  found  sweet,  unsalted  butter, 
stored  at  a  temperature  of  about  10°  below  zero  Fahren- 
heit. This  is  usually  secured  by  contract  from  whole  milk 


FIG.  44.  —  Sweet  cream  receivers  in  Collins  Bros.'  factory. 

creameries,  and  is  of  very  good  quality  being  "  June  extras" 
and  "  Fall  extras." 

To  prepare  the  materials  for  the  freezer,  butter  and 
milk  are  placed  in  proper  proportions  in  a  mixing  vat, 
heated  to  about  140°  F.,  and  agitated  to  form  an  emulsion, 
then  passed  through  the  homogenizer.  The  emulsion  issues 
from  this  machine  as  a  homogeneous  cream,  thoroughly 
pasteurized  and  with  the  fat  thoroughly  and  permanently 


178  DAIRY  TECHNOLOGY 

incorporated  in  the  serum.  The  flavor  of  this  cream, 
however,  is  not  so  fine  as  that  of  the  fresh,  natural  prod- 
uct. Upon  leaving  the  homogenizer,  the  cream  is  cooled 
nearly  to  the  freezing  point  and  pumped  back  into  hold- 
ing vats  in  the  cold  room  just  as  is  done  with  the  milk. 

In  such  a  factory  as  this,  operating  on  so  large  a  scale, 
the  difficulty  of  securing  a  sufficient  quantity  of  fresh 
sweet  cream  can  easily  be  comprehended.  The  advantage 
of  using  homogenized  cream  made  from  butter  and  milk 
is  very  evident.  In  addition  to  this,  the  homogenized 
cream  is  very  viscous  and  can  be  used  immediately, 
while  ordinary  pasteurized  cream  must  be  held  at  a  low 
temperature  for  about  a  day  in  order  to  regain  its  vis- 
cosity. It  would  be  very  inconvenient  and,  in  some  in- 
stances, difficult  to  hold  in  storage  such  vast  quantities  of 
cream. 

Making  the  Mix.  —  The  cream  is  drawn  from  the 
storage  vats  as  wanted,  a  definite  quantity  being  placed 
in  a  mixing  vat  where  the  sugar,  flavor,  and  binder  are 
added,  exact  quantities  being  weighed  in.  These  mix- 
tures are  dissolved  and  thoroughly  mixed  with  the  cream 
by  means  of  an  agitating  device.  The  mixer  is  also  a 
cooler,  brine  being  pumped  through  the  agitator. 

Freezing  and  Hardening.  —  The  mix  being  made,  it 
is  piped  to  the  supply  tanks  of  the  freezers.  Near  these 
tanks  are  several  freezers,  some  continuous  and  some 
batch  brine  freezers.  During  the  rush  season  these  ma- 
chines are  busy  turning  out  their  frozen  delicacy  for  twelve 
or  more  hours  per  day.  As  soon  as  a  packing  can  is  full, 
a  sheet  of  parchment  paper  is  placed  over  the  top,  then 
the  metal  cover  is  put  on,  and  the  can  is  put  into  the  hard- 
ening room,  a  room  held  at  about  the  zero  point,  being 
cooled  by  artificial  refrigeration.  Here  the  cans  remain 


ICE-CREAM  FACTORIES 


179 


for  about  twenty-four  hours  until  the  cream  is  thoroughly 
hardened  all  through  and  until  taken  out  for  shipment. 

To  prepare  the  cream  for  shipping,  the  cans  are  placed 
in  a  tub  and  packed  with  salt  and  ice. 

Artificial  refrigeration  is  employed  for  all  the  cooling, 


FIG.  45.  —  Ice-cream  hardening  room  in  Wheat's  factory. 

using  the  direct  expansion  in  the  storage  and  hardening 
rooms,  and  brine  for  the  cooling  coils  and  freezers.     The 
factory  makes  all  its  own  artificial  ice  used  in  the  packing 
cans  for  shipment. 
In  one  style  of  hardening  room,  the  cans  are  placed 


180  DAIRY  TECHNOLOGY 

upon  shelves  where  small  streams  of  brine  play  upon 
them.  The  brine  drains  to  certain  points,  is  pumped  back 
to  the  tank,  recooled  and  circulated  again.  Or  the  cans 
may  be  placed  in  tanks  of  brine  until  the  cream  hardens. 
Either  style  makes  a  more  or  less  sloppy  hardening  room, 
and  although  the  cooling  is  very  efficient,  these  styles  are 
not  being  used  so  widely  as  the  dry  hardening  room. 

A  hardening  room  which  employs  the  dry  system  is 
cooled  by  ammonia  expansion  coils.  A  uniform  tempera- 
ture is  maintained  and  the  rapidity  of  the  hardening  in- 
creased by  continuous  air  currents  generated  by  electric 
fans. 

Standardization  of  Cream.  —  This  topic  is  treated  under 
"  City  Milk  Supply,"  but  some  modifications  are  necessary 
when  materials  other  than  milk  and  cream  are  used.  It 
must  be  remembered  that  the  sugar,  flavoring,  etc.,  added 
to  the  cream  have  similar  effects  in  reducing  the  percentage 
of  fat  as  has  the  addition  of  skim  milk.  Therefore,  if  we 
add  8  pounds  of  sugar  to  45  pounds  of  cream  containing 
20  per  cent  fat,  the  sweetened  cream  will  contain  a  con- 
siderably smaller  percentage  of  fat.  45  pounds  of  20- 
per-cent  cream  contain  9  pounds  of  fat;  then  53  pounds 
(45  +  8  =  53)  of  the  sweetened  cream  contain  9  divided 
by  53  times  100,  which  equals  17  per  cent  fat.  Using  the 
formula  45  pounds  of  cream,  8  pounds  of  sugar,  4  ounces 
of  flavoring  extract,  4  ounces  gelatine,  to  make  a  ic-gallon 
batch  of  ice  cream,  if  the  maker  wishes  his  finished  product 
to  contain  14  per  cent  fat,  what  per  cent  of  fat  should  he 
have  in  his  cream?  The  total  weight  of  materials  is  45 
pounds  of  cream  plus  8  pounds  sugar,  plus  J  ounce  flavor 
extract  plus  J  ounce  gelatine.  This  equals  53.5  pounds. 
If  the  per  cent  of  fat  is  14,  or  the  minimum  law  standard, 
this  amount  of  ice  cream  mix  contains  7.49  pounds  of 


ICE-CREAM   FACTORIES  181 

butter  fat.  Then  the  45  pounds  of  cream  must  contain 
7.49  pounds  of  fat  or  (7.49  divided  by  45  times  100)  16.6 
per  cent  of  fat. 

Every  ice-cream  factory  should  standardize  the  cream. 
The  range  between  the  minimum  per  cent  of  fat  (usually 
specified  by  law)  and  the  maximum  per  cent  of  fat  de- 
sirable is  rather  narrow. 


CHAPTER  XXI. 

SCORING  ICE  CREAM. 

Proposed  Score  Cards.  —  There  are  two  or  more  score 
cards  being  used  tentatively  in  judging  ice  cream.  One 
of  them  is  as  follows : 1 

Flavor 45 

Body 20 

Texture 20 

Permanency 10 

Package 5 

Total 100 

Flavor.  To  be  that  of  clean,  sweet  cream  sweetened  to 
taste  with  cane  sugar;  the  score  to  be  cut  for  any  flavor 
of  sour  cream  and  cut  severely  for  any  dirty  flavor,  and 
but  little  if  too  sweet  or  not  sweet  enough,  or  if  the  added 
flavor  is  too  high  or  too  low,  for  these  are  largely  regulated 
by  trade  demands. 

Body.  To  be  firm,  mellow  and  slightly  elastic  under 
pressure  of  the  finger  at  a  temperature  of  18°  F.,  or  less. 
It  must  not  be  rubbery  or  too  weak. 

Texture.  To  be  smooth,  creamy  and  free  from  coarse 
water  crystals;  the  score  to  be  cut  moderately  if  too  coarse, 
and  severely  if  inclined  to  be  sticky  or  doughy. 

Permanency.  To  have  a  reasonable  standing-up  power 
on  an  ordinarily  cool  dish,  and  to  offer  some  resistance  in 
the  mouth,  instead  of  melting  and  disappearing  as  liquid 
almost  immediately  upon  being  tasted. 

1  Vermont  Bui.  155. 
182 


SCORING  ICE  CREAM  183 

Package.   To  be  clean,  tidy  and  free  from  evidence  of 
slovenly  workmanship. 
Another  proposed  score  card  is  as  follows:1 

Flavor 45 

Texture 25 

Richness 15 

Appearance 10 

Color. 5 

Total 100 

I.    FLAVOR. 

Definition  of  Good  Ice-cream  Flavor. 
The  cream  flavor  must  be  clean  and  creamy,  and  com- 
bined with  flavoring  material  which  blends  with  the  cream 
to  a  full  and  delicious  flavor. 

Defects  in  Flavor. 

1 .  Defects  due  to  the  use  of  flavors  which  will  not  blend 
with  the  other  ingredients. 

2.  Defects  due  to  cream  used: 
Sour-cream  flavor. 
Old-cream  flavor. 
Bitter-cream  flavor. 
Metallic-cream  flavor. 
Oily-cream  flavor. 
Weedy-cream  flavor. 

Barn  flavor. 

Unclean  flavor. 

Burned  or  overheated  flavor. 

3.  Defects  in  flavor  due  to  filler  used: 
Condensed-milk  flavor. 

Starch  flavor. 
Gum  flavor. 
Gelatine  flavor. 

1  Iowa  Bui.  123. 


184  DAIRY  TECHNOLOGY 

4.   Defects  in  flavor  due  to  other  ingredients: 
Too  sweet. 
Lack  of  sweetness. 

Coarse  flavor  due  to  flavoring  material. 
Stale-fruit  flavor. 
Rancid-nut  flavor. 
Mouldy-nut  flavor. 

II.  TEXTURE  : 

Definition  of  a  Good  Texture. 

The  cream  must  be  firmly  frozen  and  be  smooth  and 
velvety. 

Defects  in  Texture. 

Icy.  This  defect  is  most  noticeable  toward  the  bottom 
of  the  container  and  may  be  due  to  improper  packing  or 
by  holding  too  long  ice  cream  which  was  manufactured 
without  filler. 

Coarse.  This  defect  may  be  due  to  the  use  of  too  thin 
cream  or  to  packing  while  too  soft. 

Sticky.  This  is  due  to  fillers  such  as  gelatine,  sweetened 
condensed  milk,  glucose,  etc. 

Buttery.  This  defect  is  due  to  the  use  of  cream  which 
has  been  partially  churned  before  freezing,  or  to  cream 
which  enters  the  freezer  at  too  high  a  temperature.  It 
may  also  be  due  to  operating  the  freezer  at  too  high  speed 
or  to  some  defect  in  the  construction  of  the  freezer. 

Too  Soft.   Due  to  improper  packing  after  freezing. 

When  judging  cream  containing  nuts,  fruits,  etc.,  due  al- 
lowance should  be  made  for  the  presence  of  such  ingredients. 

III.  RICHNESS  : 

Ice  cream  containing  the  amount  of  butter  fat  required 
by  the  state  pure-food  law  should  be  considered  perfect 
in  richness. 


SCORING  ICE   CREAM  185 

The  richness  is  determined  by  making  chemical  analysis 
for  fat. 

IV.  APPEARANCE  : 

Ice  cream  scoring  perfect  in  appearance  should  be  clean 
and  neatly  put  up  and  in  a  clean  container. 

Dejects.  Cream  of  unclean  appearance;  lack  of  parch- 
ment circle  over  ice  cream;  dirty  container;  rusty  con- 
tainer; dirty  ice-cream  tub;  old  tag  strings  attached  to 
handle  of  tub. 

When  judging  brick  ice  cream  special  attention  should 
be  given  to  the  uniformity  of  the  layers,  to  the  neat  fold- 
ing of  the  parchment  wrapper  and  to  cleanliness  and  general 
appearance  of  the  package. 

V.  COLOR: 

Ice  cream  of  perfect  color  is  such  as  contains  only  the 
natural  color  imparted  to  it  by  the  flavoring  materials 
used.  If  color  is  added  it  should  harmonize  with  the  par- 
ticular flavoring  used. 

Defects  in  Color.  Too  high  color;  unnatural  color  such 
as  colors  different  from  the  color  of  the  natural  flavoring 
material  used. 

Individual  molds,  if  colored,  should  be  as  nearly  as 
possible  the  same  color  as  the  object  they  represent. 


CHAPTER  XXII. 
ICE-CREAM  STANDARDS. 

Ax  the  present  time  there  is  considerable  agitation 
in  the  ice-cream  world  over  the  pure-food  standards  that 
relate  to  the  composition  of  ice  cream.  Undoubtedly, 
the  most  important  part  of  the  laws  pertaining  to  the 
manufacture  of  ice  cream  is  that  requiring  that  the  prod- 
uct shall  be  made  under  sanitary  conditions  and  shall 
contain  nothing  deleterious  to  health.  This  portion  of 
the  present  laws  is  generally  satisfactory  to  every  one. 

Binders  and  Fillers.  —  In  some  states  and  cities  there 
are  laws  or  ordinances  providing  for  a  fat  standard  and 
regulating  the  kind  and  amount  of  filler  or  binder  used. 
The  large  city  ice-cream  manufacturers  as  a  whole  are 
opposed  to  standards.  In  regard  to  binders  it  may  be 
said  that,  providing  the  binder  is  a  healthful  substance, 
there  should  be  no  ruling  against  it  by  any  pure-food  law. 
Gelatine  and  gum  tragacanth  are  used  in  ice  cream  to  give 
it  a  smooth  texture  and  prevent  granulation  and  crystalli- 
zation of  the  watery  parts  while  in  storage,  and  there 
seems  to  be  no  good  reason  for  classing  them  as  adulter- 
ants. But  the  use  of  corn  starch,  rice  and  wheat  flour, 
and  other  fillers  to  hide  a  lack  of  butter  fat  must  be  con- 
demned, when  the  product  is  sold  under  the  name  of  ice 
cream.  Large  amounts  of  fillers  are  seldom  used  when 
the  fat  standard  is  enforced. 

Fat  Standard.  —  The  fat  content  of  ice  cream  is  a  much- 
discussed  subject.  The  justice  of  a  fat  standard  seems 

186 


ICE-CREAM  STANDARDS  187 

to  depend  upon  whether  the  consumer,  the  people  as  a 
whole,  consider  ice  cream  to  be  frozen  cream,  or  merely 
a  frozen  delicacy  with  a  creamy  consistency.  Many 
ice-cream  manufacturers  maintain  that  the  latter  is  the 
case,  and  that  there  is  no  more  necessity  for  a  fat  standard 
for  ice  cream  than  there  is  for  a  fat  standard  for  cream 
gravy  or  creamed  potatoes.  They  claim  that  since  the 
product  is  not  necessarily  purchased  because  of  its  food 
value,  there  should  be  no  standard  for  the  amount  of 
nutrients  contained  therein.  But  if  the  first-mentioned 
definition  holds,  then  the  fat  standard  for  ice  cream  is 
perfectly  just  and  legitimate.  However,  under  any  con- 
ditions, it  seems  hardly  fair  to  the  consumer  or  to  the 
manufacturers  to  sell  a  product  containing  7  per  cent 
of  butter  fat  under  the  same  name  as  that  containing 
14  per  cent  of  butter  fat. 

If  another  material  (milk)  is  used  in  the  manufacture 
of  a  frozen  product,  an  appropriate  name  should  distin- 
guish it  from  other  frozen  products,  just  as  the  name 
"  Water  Ice  "  is  used  to  distinguish  that  product  from  ice 
cream.  A  frozen  product  made  of  milk  can  be  manu- 
factured and  sold  at  a  much  lower  cost  than  that  made 
of  cream.  Such  a  product  could  be  called  "Ice  Milk." 
The  consumer  might  then  obtain  a  cheap  refreshment  at 
a  proper  price;  and  he  may  also,  if  he  desires,  obtain  a 
product  of  higher  quality  and  be  certain  of  getting  it  by 
paying  the  higher  price  for  the  richer  product,  properly 
called  ice  cream. 

In  South  Dakota,  the  i4-per-cent  fat  standard  is  being 
enforced.  Several  cases  were  brought  to  the  attention 
of  the  dairy  inspection  department  in  which  some  facto- 
ries located  in  large  cities  were  selling  so-called  ice  cream 
at  a  very  low  price.  This  product  contained  from  6  to 


l88  DAIRY  TECHNOLOGY 

10  per  cent  of  butter  fat.  The  local  and  small  ice-cream 
factory  made  a  product  containing  14  per  cent  of  fat.  It 
was  impossible  for  this  latter  factory  to  compete  with 
the  other  factories  manufacturing  the  inferior  article. 
The  product  shipped  in  from  the  large  plant  contained  from 
6  to  10  per  cent  of  fat,  and  contained  an  excess  of  filler. 
A  good  product  can  thus  easily  be  driven  from  the  market 
by  a  cheap  substitute.  It  is  apparently  proper  that 
there  should  be  a  law  to  protect  the  consumers  as  well  as 
those  who  desire  to  place  a  superior  article  on  the  market. 
Under  a  proper  classification  these  two  products  would 
have  been  sold  under  different  names  and  would  not  have 
come  into  such  sharp  competition  with  each  other. 

The  increasing  magnitude  of  the  ice-cream  industry 
makes  necessary  the  adoption  of  appropriate  trade  names 
for  all  the  various  ices.  Several  classifications,  varying  in 
complexity,  have  been  proposed.  This  may  be  taken  as 
an  indication  of  a  general  desire  to  establish  well-defined 
classes  of  frozen  products,  and  it  seems  eminently  fitting  to 
make  a  distinction  in  name  between  the  products  made  of 
milk  and  those  made  of  cream. 

Testing  Ice  Cream.  —  The  presence  of  sugar,  gelatine 
and  gum  in  ice  cream  makes  necessary  some  modifica- 
tion of  the  Babcock  Test  in  order  to  secure  good  results. 

The  following  method  is  suggested;  it  is  comparatively 
simple  and  produces  a  very  clear  reading. 

i.  The  Hydrochloric  and  Acetic-acid  Method. — Nine 
grams  of  the  sample  are  weighed  into  the  test  bottle 
and  30  cubic  centimeters  of  a  mixture  of  equal  parts 
by  volume  of  concentrated  hydrochloric  acid  and  80  per 
cent  acetic  acid  are  added.  Mix  thoroughly  and  heat 
on  the  water  bath  till  the  mixture  darkens,  but  avoid 
charring.  Whirl  in  the  centrifuge,  add  hot  water  as 


ICE-CREAM   STANDARDS  189 

in  the  regular  testing  and  read  the  percentage  of  fat 
directly. 

If  charring  has  interfered  with  the  fat  reading,  add 
ether  after  whirling  to  dissolve  the  fat,  and  draw  off  the 
ether  solution  into  another  bottle.  Evaporate  off  the 
ether,  fill  with  hot  water  and  again  whirl  and  read.  This 
latter  method  should  not  be  resorted  to  except  in  cases 
of  necessity.  It  is  always  better  to  run  the  test  over, 
provided  there  is  enough  left  of  the  original  sample. 

2.  Modified  Babcock  Method.  —  Ice  cream  can  be  tested 
successfully  by  using  sulphuric  acid,  provided  certain  pre- 
cautions are  observed.  The  writers  have  obtained  good 
results  by  using  the  following  method.  Melt  the  sample 
slowly  at  a  low  temperature  to  a  creamy  consistency; 
quickly  weigh  9  grams  of  it  into  a  milk  bottle.  Add  about 
twelve  cubic  centimeters  soft  water,  mix,  then  succes- 
sively add  small  quantities  of  sulphuric  acid,  mix  and  let 
stand  to  permit  the  acid  to  act.  The  action  of  the  acid 
is  indicated  by  the  color  of  the  mixture,  and  when  this 
assumes  a  strong  coffee  color  the  reaction  has  gone  far 
enough  and  no  more  acid  is  required.  If  the  color  con- 
tinues to  darken,  add  a  small  quantity  of  soft  water  to 
prevent  charring. 

Bacteria  in  Ice  Cream.  —  The  subject  of  bacteria  in  ice 
cream  has  received  attention  only  during  the  past  few 
years.  There  is  a  popular  belief  that,  because  cream  is 
frozen,  it  cannot  decompose  and  that  the  organisms  origi- 
nally in  the  cream  are  either  killed  or  rendered  harmless 
by  the  continued  low  temperature.  However,  experiments 
show  that  bacteria  do  remain  virile  and  that  certain  types 
even  proliferate  at  sub-freezing  temperatures.  The  bac- 
terial content  of  ice  cream,  then,  is  a  matter  of  importance 
from  a  hygienic  standpoint. 


igo  DAIRY  TECHNOLOGY 

We  have  previously  noted  that  the  conditions  of  the  milk 
and  cream  supply  in  many  localities  are  far  from  ideal. 
Since  milk  and  cream  are  the  main  constituents  of  ice 
cream,  this  latter  product  cannot  be  of  any  better  quality 
than  the  materials  of  which  it  is  made.  However,  all 
methods  of  improving  milk  and  cream  are  just  as  applicable 
to  the  ice-cream  industry  as  to  city  milk  supply. 

Investigations  of  conditions  in  Washington,  D.  C.,  re- 
ported in  Bulletin  56  of  the  Hygienic  Laboratory,  show 
that,  in  1907,  in  130  samples  of  cream  examined,  the  average 
number  of  bacteria  per  cubic  centimeter  was  12,130,080. 
At  the  same  time,  381  samples  of  milk  were  subjected  to 
a  bacteriological  examination  and  the  average  number  of 
organisms  per  cubic  centimeter  was  3,415,533.  Samples 
of  ice  cream  at  the  same  time  contained  from  100,000  to 
400,000,000  bacteria  per  cubic  centimeter. 

Dr.  George  W.  Stiles  of  Washington,  D.  C.,  investigated 
the  bacterial  flora  of  ice  cream  in  cold  storage,  and  secured 
the  following  results: 

Four  samples  of  ice  cream  were  secured  from  different 
dealers  and  placed  in  storage  at  a  temperature  varying  from 
o°  to  10°  F.  The  bacterial  content  of  these  samples  aver- 
aged on  the 

Per  c.c. 

Initial  count 70,000,000 

3rd  day 120,000,000 

6th  day 65,000,000 

gth  day 80,000,000 

nth  day 50,000,000 

i4th  day 13,000,000 

i7th  day 21,000,000 

2oth  day 85,000,000 

23rd  day 90,000,000 

27th  day 225,000,000 

30th  day 22,000,000 

34th  day 13,000,000 


ICE-CREAM   STANDARDS  191 

Just  what  significance  should  be  attached  to  these  bac- 
terial counts  depends  chiefly  upon  the  types  or  kinds  of 
organisms  that  are  present  in  the  ice  cream.  Certain 
varieties  may  produce  toxins,  while  others  are  harmless. 

Cases  are  on  record  where  ice  cream  caused  digestive 
derangements,  headache,  diarrhea  and  symptoms  of 
poisoning  soon  after  the  eating.  Such  cases  of  illness  are 
commonly  explained  as  ptomaine  poisoning  and  are  usually 
due  to  unsanitary  conditions  of  the  raw  material  (cream, 
gelatine,  etc.),  the  ice-cream  factory,  or  prolonged  storage 
of  the  ice  cream. 

The  owners  of  one  large  ice-cream  factory  guarantee 
their  product  sold  to  be  absolutely  free  from  tubercle 
bacilli,  and  other  disease-producing  bacteria,  and  to  contain 
no  more  than  25,000  germs  per  cubic  centimeter  when 
delivered  to  the  consumer.  At  this  particular  plant  a  bac- 
terial count  is  made  of  all  the  cream  to  be  frozen.  Separate 
counts  are  made  (i)  of  the  cream  after  homogenization,  (2) 
of  the  mix  before  freezing  and  (3)  of  the  frozen  product 
ready  for  shipment.  The  counts  run,  on  an  average,  about 
as  follows:  cream,  2000  bacteria  per  cubic  centimeter; 
mix,  12,000  per  cubic  centimeter,  and  ice  cream  24,000 
per  cubic  centimeter.  The  ice  cream  is  also  tested  for 
gas-producing  organisms,  any  bacteria  of  the  B.  Coli 
type  being  considered  a  very  objectionable  contamination. 
The  analysis  report  card  used  in  this  work  is  as  follows: 


192  DAIRY  TECHNOLOGY 

BACTERIOLOGICAL  ANALYSIS  OF  ICE  CREAM.1 

Ice  cream  examined 

No.  of  Plates  used  for  each  dilution 

Average  number  of  Bacteria  in  dilution i-        100 Per  c.c. 

"          I-       1,000 "        " 

"       i-     5,000 "      " 

"       i-  10,000 "      " 

"       1-100,000 "      " 

Total  average  of  Bacteria "     " 

Gas %  Co2 %  H2 %  B.  Coli  Communis 

Date  cream  made 19 .. 

Date  of  analysis 19 .. 

Date  plates  '  'counted' ' 19 ..  Signed 

Bacteriologist. 
1  Collins  Bros.,  Chicago,  111. 


CHAPTER  XXIII. 

MECHANICAL  REFRIGERATION. 

MECHANICAL  refrigeration  has  been  considered  expensive 
and  impracticable  on  a  small  scale  until  within  a  few  years. 
The  science  of  producing  cold  artificially  has  been  simplified 
and  reduced  to  such  a  practical  basis  that  it  is  now  used  in 
many  large  as  well  as  small  plants  where  formerly  natural 
ice  was  used  altogether.  The  chief  factors  affecting  the 
cost  of  mechanical  refrigeration  may  be  said  to  be  similar 
to  those  affecting  the  economic  running  of  the  remaining 
machinery,  such  as  kind  of  fuel  used,  skill  of  fireman,  style 
and  condition  of  boiler,  proportion  of  boiler  power  to  work 
done,  upon  the  correlative  size  of  all  machinery,  upon 
kind  of  insulation  and  care  of  cooling-rooms  and  upon 
efficiency  of  compressor  and  whole  refrigerating  system. 

Chemicals  Used.  —  The  most  common  substances  used 
in  mechanical  refrigeration  are  ammonia  and  carbonic 
acid.  A  number  of  others  are  in  use,  but  from  a  creamery 
standpoint  these  only  are  of  importance.  Ammonia  is 
used  chiefly.  It  is  efficient,  cheap,  and  not  so  dangerous 
to  life  and  property  as  are  some  of  the  others.  Anhydrous 
ammonia  has  a  boiling-point  of  27°  below  zero  at  atmos- 
pheric pressure.  The  latent  heat  of  ammonia  is  also 
great.  Ammonia  has  great  chemical  stability  and  is  not 
explosive  in  nature.  Ammonia  attacks  copper  and  brass, 
but  has  no  effect  upon  iron  and  steel  pipes. 

If  ammonia  should  escape  through  a  leak  into  a  room, 
the  operator  can  protect  himself  from  the  effects  of  the 
gas  by  breathing  through  a  wet  sponge  held  in  the  mouth. 

193 


IQ4  DAIRY  TECHNOLOGY 

Ammonia  leaks  may  be  detected  by  holding  a  glass  rod 
dipped  in  hydrochloric  acid  to  the  places  where  the  leaks 
are  suspected.  When  ammonia  comes  in  contact  with 
hydrochloric  acid,  white  fumes  are  formed. 

Principles  of  Producing  Cold  Artificially.  —  The  chief 
principle  involved  in  producing  artificial  cold  is  that  when 
a  substance  passes  from  a  liquid  into  a  gaseous  state,  a 
definite  amount  of  latent  heat  is  absorbed.  When  water 
in  a  kettle  on  the  stove  begins  to  boil  and  passes  off 
into  steam,  no  higher  temperature  can  be  reached.  No 
matter  how  much  heat  is  applied  under  those  same  condi- 
tions, the  temperature  remains  the  same.  This  extra  heat 
is  used  in  transforming  the  water  into  steam.  If  this 
steam  were  confined,  and  that  heat  removed  by  cooling, 
the  steam  would  again  pass  into  a  liquid  state.  We  are 
familiar  with  the  coolness  produced  by  rapid  evaporation 
of  perspiration  from  the  body.  Mechanical  refrigeration 
is  virtually  a  process  of  evaporation  of  the  cooling  medium 
during  which  heat  is  absorbed;  and  then  again  liquefying 
the  cooling  medium  by  compression  and  cooling  to  remove 
the  absorbed  heat.  To  increase  the  ability  of  the  cooling 
medium  to  absorb  heat  the  cooling  medium  is  compressed 
and  liquefied.  So  we  might  say  that  any  compression 
refrigerating  system  has  three  separate  operations  necessary 
to  form  the  complete  cycle  of  mechanical  refrigeration, 
viz.: 

1.  Compression  of  the  ammonia  gas. 

2.  Condensation  of  the  ammonia  gas. 

3.  Expansion  of  the  ammonia  gas. 

i.  The  machine  which  causes  the  compression  of  the 
ammonia  gas  is  called  the  compressor.  In  construction 
it  is  much  like  a  steam  engine.  Small  machines  are  single 
but  large  machines  are  double  acting.  Gas  is  drawn  in 


MECHANICAL  REFRIGERATION  195 

on  the  suction  stroke,  compressed  and  discharged  on  the 
return  stroke.  The  pressure  generated  varies  between 
1 20  and  175  pounds  per  square  inch.  During  the  com- 
pression, heat  is  developed  in  proportion  to  pressure  ex- 
erted. The  greater  the  pressure,  the  higher  the  tempera- 
ture of  the  gas.  Part  of  the  heat  of  compression  is  carried 
off  by  means  of  a  continuous  stream  of  water  running 
through  a  jacket  around  the  cylinder. 

2.  From  the  compressor  the  gas  is  forced  through  the 
pipes  into  the  condensing  coils,  in  which  the  warm  com- 
pressed gas  is   cooled   still  more.     When   sufficient  heat 
has  been  removed  from  this  gas,  it  assumes  a  liquid  con- 
dition and  is  ready  to  expand  into  a  gaseous  form  for  the 
purpose  of  absorbing  heat  and  producing  cold.     During 
the  cooling  and  condensing  processes  each  pound  of  ammo- 
nia parts  with  about  five  hundred  and  sixty  units  of  heat, 
which  amount  can  again  be  absorbed  when  it  expands 
into  gas  at  the  lower  pressure. 

3.  This  liquefied  gas,  which  is  still  under  great  pressure, 
is  then  admitted  through  what  is  termed  the  expansion 
valve.     This  valve  is  especially  constructed  for  that  pur- 
pose, and  has  only  a  very  minute  opening  in  it  for  the 
admission  of  the  liquid  ammonia.     On  the  expansion  side 
the  pressure  is  low  (20  to  30  pounds) .     As  the  liquid  ammo- 
nia emerges  from  the  high-pressure  side  through  the  ex- 
pansion valve   into  the  expansion   side   it   forms  a  gas. 
This  expanded  gas  may  then  be  circulated  through  coils 
for  cooling  purposes.     From  there  it  passes  back  into  the 
suction  side  of  the  compressor  ready  to  go  through  another 
similar  cycle. 

From  the  above  description  it  will  be  seen  that  there 
are  two  sides  to  the  system,  the  expansion  side  and  the 
compression  side.  The  compression  side  extends  from 


196  DAIRY  TECHNOLOGY 

the  compressor  to  the  expansion  valve;  the  expansion 
side  from  the  expansion  valve  to  the  suction  side  of  the 
compressor,  inclusive. 

Transferring  the  Cold.  —  The  methods  of  transferring 
the  cold  to  the  different  places  in  the  building  vary.  There 
are  two  systems: 

1.  Direct  Expansion. 

2.  Brine  System. 

1.  By    the    direct-expansion    system    the    condensing 
pipes  of  the  system  are  extended  to  the  room  or  place 
at  which  the  cooling  is  to  be  done.      An  extended  set  of 
expansion  coils  then  conveys  the  gas  which  absorbs  the 
heat.     A   lower    temperature    can   be   produced   by    this 
method  than  with  the  brine  system. 

2.  In  the   brine  system  a  large  brine   tank  is  placed 
somewhere  in  the  creamery  or  ice-cream  plant  at  a  place 
most  convenient  with  respect  to  cooling.     This  tank  con- 
tains a  strong  solution  of  brine.     The  chief  reason  why 
brine  is  used  in  preference  to  water  is  that  brine  has  a 
very  low  freezing-point.     This  varies  with  different  de- 
grees of  saturation. 

Either  sodium  chloride  (common  salt)  or  calcium  chlo- 
ride may  be  used  for  brine.  The  latter  is  considered  best 
chiefly  because  it  is  not  so  hard  on  the  pipes,  and  it  keeps 
the  brine  pipes  cleaner  than  does  a  salt  brine.  The  follow- 
ing tables  give  properties  of  brine  made  from  these  two 
substances. 

The  expansion  coils  pass  through  the  brine  tank  and 
cool  the  brine.  Special  pumps  force  the  cold  brine  through 
pipes  to  the  cooling  room,  cream  vat,  cooling  coils,  ice- 
cream freezer,  etc. 


MECHANICAL   REFRIGERATION 


I97 


SHOWING  PROPERTIES  OF  SOLUTION  OF  SALT.     (Siebly.) 
(Chloride  of  Sodium.) 


Per 
cent  of 
salt  by 
weight. 

Pounds 
salt  per 
gallon  of 
solution. 

Degrees 
on  salom- 
eter 
60°  F. 

Weight 
per  gallon 
at  39°  F. 

Specific 
gravity  at 
39°  F.      - 
4°C. 

Specific 
heat. 

Freez- 
ing- 
point 
Fahr. 

Freezing- 
point 
Celsius. 

I 

0.084 

4 

8.40 

1  .007 

0.992 

30.5 

-0.8 

2 

0.  169 

8 

8.46 

I.OI5 

0.984 

29-5 

-i-5 

2-5 

O.  212 

IO 

8.50 

.019 

0.980 

28.6 

-1-9 

3 

o.  256 

12 

8-53 

.023 

0.976 

27.8 

-2.3 

3-5 

0.300 

14 

8.56 

.026 

0.972 

27.1 

-2.7 

4 

0-344 

16 

8-59 

.030 

0.968 

26.6 

-3-o 

5 

0-433 

20 

8.65 

•037 

0.960 

25.2 

-3-8 

6 

0-523 

24 

8.72 

•  045 

0.946 

23-9 

-4-5 

7 

0.617 

28 

8.78 

1-053 

0.932 

22.5 

-5-3 

8 

0.708 

32 

8-85 

i  .061 

0.919 

21.2 

-6.0 

9 

0.802 

36 

8.91 

1.068 

0.905 

19.9 

-6.7 

10 

0.897 

40 

8.97 

i  .076 

0.892 

l8.7 

-7-4 

12 

i  .092 

48 

9.  10 

i  .091 

0.874 

16.0 

-8.9 

15 

1.389 

60 

9.  26 

•US 

0-855 

12.2 

—  II.  0 

20 

1.928 

80 

9.64 

•155 

0.829 

6.1 

—  14.4 

24 

2.376 

96 

9.90 

.187 

0-795 

I  .2 

-17.1 

25 

2.488 

TOO 

9-97 

.  196 

0.783 

o-5 

-17.8 

26 

2.610 

IO4 

10.04 

.204 

0.771 

—  I.I 

-18.4 

PROPERTIES  OF  SOLUTION  OF  CHLORIDE  OF  CALCIUM. 

(Siebly.) 


Per  cent  by 
weight. 

Specific  heat. 

Specific  gravity 
at  60°  Fahr. 

Freezing-point  in 
degrees  Fahr. 

Freezing-point  in 
degrees  Cels. 

I 

0.996 

1.009 

31 

-0-5 

5 

0.964 

1-043 

27-5 

-2-5 

10 

0.896 

1.087 

22 

-5-6 

15 

0.860 

I-I34 

15 

-9.6 

20 

0.834 

1.182 

5 

-14.8 

25 

0.790 

1-234 

-8 

—  22.1 

Use  of  Brine.  —  For  all  general  cooling  purposes,  the 
brine  system  is  more  economical  and  satisfactory  because 
the  brine  may  be  kept  cold  by  running  the  compressor 
just  a  few  hours  each  day.  The  cold  is  stored  and  used 


198  DAIRY  TECHNOLOGY 

when  wanted.  In  the  direct-expansion  system,  as  soon 
as  the  compressor  stops  refrigeration  ceases.  However, 
for  dry  hardening  rooms  the  direct-expansion  system  is 
absolutely  necessary  to  secure  and  maintain  a  sufficiently 
low  temperature. 

Strength  of  Brine.  —  The  proper  degree  of  concentra- 
tion of  the  salt  solution  depends  upon  the  temperature 
desired.  Low  temperatures  demand  a  stronger  brine  to  pre- 
vent freezing;  but  an  unnecessarily  strong  brine  is  undesir- 
able, because  the  stronger  the  brine  is,  the  less  is  its  specific 
heat;  that  is,  it  has  less  ability  to  absorb  heat,  and  too 
concentrated  brine  is  likely  to  clog  the  pipes. 

Size  of  Compressor.  —  The  size  of  a  refrigeration  ma- 
chine is  expressed  as  a  certain  number  of  tons'  capacity. 
For  instance  a  machine  of  four  tons'  capacity  means  that 
that  machine  would  produce  in  24  hours  as  much  cold  as 
is  given  off  by  four  tons  of  ice  melting  to  water  at  32°  F. 
Its  actual  ice-making  capacity  is  about  half  this  much; 
a  four-ton  machine  will  make  about  2  tons  of  ice  per  day. 

In  selecting  the  size  of  machine  needed  it  must  be 
remembered  that  the  capacity  is  rated  on  a  24-hour  run. 
If  conditions  are  such  that  it  will  be  desirable  to  run  the 
compressor  only  four  hours  per  day  then  the  machine  must 
have  six  times  the  daily  capacity  needed.  The  larger 
machines  produce  a  ton  of  refrigeration  at  less  cost  than 
small  ones,  but  in  a  general  way,  for  small  and  medium- 
sized  machines,  the  power  required  is  about  two  and  one- 
quarter  horse  power  per  ton  of  refrigeration. 

Operation  of  an  Ammonia  Plant.  —  Charging  and  operat- 
ing an  ammonia  plant  are  very  ably  discussed  by  H.  H. 
Kelley  in  The  Engineer,  from  which  the  following  is  taken. 

"  When  about  to  start  an  ice  or  refrigerating  plant,  the 
first  thing  necessary  is  to  see  that  the  system  is  charged 


MECHANICAL  REFRIGERATION  199 

with  the  proper  amount  of  ammonia.  Before  the  ammonia 
is  put  in,  however,  all  air  and  moisture  must  be  removed; 
otherwise  the  efficiency  of  the  system  will  be  seriously 
interfered  with.  Special  valves  are  usually  provided  for 
discharging  the  air,  which  is  removed  from  the  system 
by  starting  the  compressor  and  pumping  the  air  out,  the 
operation  of  gas  cylinder  being  just  the  reverse  of  that  when 
it  is  working  ammonia  gas.  It  is  practically  impossible 
to  get  all  the  air  out  of  the  entire  system  by  this  means, 
so  that  some  other  course  must  be  taken  to  remove  any 
remaining  air  after  the  compressor  has  been  started  at 
regular  work.  This  can  be  accomplished  by  admitting 
the  ammonia  a  little  at  a  time,  permitting  the  air  to  escape 
through  a  purge  valve,  the  air  being  thus  expelled  by  dis- 
placement. The  cylinder  containing  the  anhydrous  am- 
monia is  connected  to  the  charging  valve  by  a  suitable 
pipe,  and  the  valve  opened.  The  compressor  is  then  kept 
running  slowly  with  the  suction  and  discharge  valves  wide 
open  and  the  expansion  valve  closed.  When  one  cylinder 
is  emptied  put  another  in  its  place,  being  careful  to  close 
the  charging  valve  before  attempting  to  remove  the  empty 
cylinder,  opening  it  when  the  fresh  cylinder  is  connected 
up. 

"  From  sixty  to  seventy-five  per  cent  of  the  full  charge 
is  sufficient  to  start  with  so  that  the  air  may  have  an  op- 
portunity of  escaping  with  as  little  loss  of  ammonia  as 
possible.  An  additional  quantity  of  ammonia  may  then 
be  put  in  each  day  until  the  full  charge  has  been  introduced. 
When  the  ammonia  cylinders  have  been  emptied  and  a 
charge  of,  say,  seventy-five  per  cent  of  the  full  amount 
has  been  introduced,  the  charging  valve  is  closed  and  the 
expansion  valve  opened.  The  glass  gauge  on  the  ammonia 
receiver  will  indicate  the  depth  of  ammonia.  The  appear- 
ance of  frost  on  the  pipe  leading  to  the  coils  and  the  cooling 
of  the  brine  in  the  tank  will  indicate  that  enough  ammonia 
has  been  introduced  to  start  with.  It  is  sometimes  difficult 
to  completely  empty  an  ammonia  cylinder  without  first 
applying  heat.  The  process  of  cooling  being  the  same 
when  the  ammonia  expands  from  the  cylinder  into  the 


200  DAIRY  TECHNOLOGY 

system  as  when  leaving  the  expansion  valve,  a  low  temper- 
ature is  produced  and  the  cylinder  and  connections  be- 
come covered  with  frost.  When  this  occurs  the  cylinder 
must  be  slightly  warmed  in  order  to  be  able  to  get  all  the 
ammonia  out  of  it.  The  ammonia  cylinders,  when  filled, 
should  never  be  subjected  to  rough  handling  and  are 
preferably  kept  in  a  cool  place  free  from  any  liability 
to  accident.  The  fact  that  ammonia  is  soluble  in  water 
should  be  well  understood  by  persons  charging  a  refrigerat- 
ing system,  or  working  about  the  plant.  One  part  of  water 
will  absorb  about  800  parts  of  ammonia  gas  and  in  case  of 
accident  to  the  ammonia  piping  or  machine,  water  should 
be  employed  to  absorb  the  escaping  gas.  Persons  em- 
ployed about  a  plant  of  this  kind  should  be  provided  with 
some  style  of  respirator,  the  simplest  form  of  which  is  a 
wet  cloth  held  over  the  mouth  and  nose. 

"  After  starting  the  compressor  at  the  proper  speed 
and  adjusting  the  regulating  valve  note  the  temperature  of 
the  delivery  pipe,  and  if  there  is  a  tendency  to  heat,  open 
it  wider,  and  vice  versa.  This  valve  should  be  carefully 
regulated  until  the  temperature  of  the  delivery  pipe  is 
practically  the  same  as  the  water  discharged  from  the 
ammonia  condenser.  With  too  light  a  charge  of  ammonia 
the  delivery  pipe  will  become  heated  even  when  the  regulat- 
ing valve  is  wide  open.  As  a  general  thing  when  the  plant 
is  working  properly  the  temperature  of  the  refrigerator  is 
about  15°  lower  than  the  brine  being  used,  the  temperature 
of  the  water  discharged  from  the  ammonia  condenser  will 
be  about  15°  lower  than  that  of  the  condenser,  the  pointers 
on  the  gauges  will  vibrate  the  same  distance  at  each  stroke 
of  the  compressor  and  the  frost  on  the  pipes  entering  and 
leaving  the  refrigerator  will  be  about  the  same.  By  placing 
the  ear  close  to  the  expansion  valve  the  ammonia  can  be 
heard  passing  through  it,  the  sound  being  uniform  and 
continuous  when  everything  is  working  properly. 

"  When  air  is  present  the  flow  of  ammonia  will  be  more 
or  less  intermittent,  which  irregularity  is  generally  notice- 
able through  a  change  in  the  usual  sound  heard  at  the 
expansion  valve.  The  pressure  in  the  condenser  will  also 


MECHANICAL   REFRIGERATION  2OI 

be  higher  and  the  effect  of  the  apparatus  as  a  whole  will 
be  changed,  and,  of  course,  not  so  good.  These  changes 
will  be  quickly  noticed  by  a  person  accustomed  to  the  con- 
ditions obtaining  when  everything  is  in  order  and  working 
properly. 

"  The  presence  of  oil  or  water  in  the  system  is  generally 
detected  by  shocks  occurring  in  the  compressor  cylinder. 

"  In  nearly  all  plants  the  presence  of  oil  in  the  system 
of  piping  is  unavoidable.  The  oil  used  for  lubricating 
purposes,  especially  at  the  piston  rod  stuffing  boxes,  works 
into  the  cylinders  and  is  carried  with  the  hot  gas  into  the 
ammonia  piping,  where  it  never  fails  to  cause  trouble. 
The  method  of  removing  the  air  from  the  system  has  al- 
ready been  referred  to,  but  the  removal  of  oil  is  accomplished 
by  means  of  an  oil  separator.  This  is  placed  in  the  main 
pipe  between  the  compressor  and  the  condenser,  and  is 
of  about  the  size  of  the  ammonia  receiver.  Sometimes 
another  oil  separator  is  placed  in  the  return  pipe  close  to 
the  compressor  which  serves  to  eliminate  any  remaining 
oil  in  the  warmer  gas  and  to  remove  pieces  of  scale  and 
other  foreign  matter  which,  if  permitted  to  enter  the  com- 
pressor cylinder,  would  tend  to  destroy  it  in  a  very  short 
time. 

"  The  oil,  which  always  gets  into  the  system  sooner  or 
later  and  in  greater  or  less  quantity,  depending  upon  the 
care  exercised  to  avoid  it,  acts  as  an  insulator  and  pre- 
vents the  rapid  transfer  of  heat  from  the  ammonia  to 
the  pipe,  .and  also  occupies  considerable  space  that  is  re- 
quired for  the  ammonia  where  the  be&t  results  are  to  be 
obtained." 

Insulation.  —  Where  mechanical  refrigeration  is  used  the 
insulation  of  cooling  rooms,  brine  tank  and  pipes  is  of  great 
importance  from  an  economic  point  of  view. 

The  insulating  material  must  be  a  non-absorbent  of 
moisture,  a  poor  conductor  of  heat,  and  of  sufficient  strength 
and  durability  to  remain  for  many  years  without  crumbling 
or  decomposing. 


202  DAIRY  TECHNOLOGY 

All  ammonia  and  brine  pipes  passing  through  rooms 
where  refrigeration  is  not  desired  should  be  covered  with 
insulation  two  inches  thick  for  temperatures  of  zero  or 
below,  and  one  to  one  and  a  half  inches  for  higher 
temperatures. 

According  to  the  H.  W.  Johns-Mansfield  Co.,  there  is  a 
loss  of  nine  tons  of  refrigeration  on  account  of  radiation  in 
24  hours  on  500  feet  of  3^ -inch  brine  pipe  with  temperature 
of  zero  and  outside  temperature  of  70°  F.  Figuring  the 
cost  of  refrigeration  at  50  cents  per  ton,  the  loss  would  be 
$4.50  per  day  of  24  hours. 


PART    IV. 

BY-PRODUCTS   OF   THE   CREAMERY 
AND   CHEESE  FACTORY. 

CHAPTER  XXIV. 

COTTAGE  CHEESE. 

Cottage  Cheese.  —  Cottage  cheese  (Dutch  cheese,  or 
Schmier-kase)  is  a  product  that  usually  finds  a  ready  sale 
on  the  market  at  a  price  that  insures  a  good  profit  to  the 
manufacturer.  Especially  is  this  true  in  large  cities  and 
in  mining  districts  during  hot  weather. 

In  the  past  this  product  was  made  mostly  in  the  home, 
and  varied  greatly  in  quality  and  general  characteristics. 
But  at  the  present  time,  large  quantities  of  it  are  being 
manufactured  in  whole  milk  creameries,  large  dairies,  etc. 
In  order  that  a  manufacturer  may  turn  out  a  uniform 
product,  a  definite  method  of  manufacture  should  be  fol- 
lowed. The  process  admits  of  a  number  of  variations  in 
its  details,  hence  judgment  must  be  used  by  the  manufac- 
turer in  adopting  the  process  most  suitable  to  his  particular 
conditions,  kind  of  raw  material,  and  market  demands. 

Milk  to  Use.  —  In  making  cottage  cheese,  just  as  in 
all  other  dairy  products,  it  is  essential  to  have  a  fresh, 
clean,  pure  raw  material  to  start  with.  Undesirable  odors 
and  flavors  in  the  milk  seriously  affect  the  finished  product. 

Skim  milk  rather  than  whole  milk  is  used  in  cottage- 
cheese  making,  because  in  the  use  of  whole  milk  a  large 
percentage  of  the  fat  is  lost  in  the  whey.  If  a  rich,  creamy 

•  203 


204  DAIRY  TECHNOLOGY 

cheese  is  desired,  it  can  be  secured  more  economically  by 
using  skim  milk,  and  then  adding  cream  to  the  finished 
product. 

A  good  quality  of  cottage  cheese  can  be  manufactured 
from  good  buttermilk.  Skim  milk  and  buttermilk  together 
may  be  used  in  various  proportions. 

Use  of  Starters.  —  In  order  to  insure  a  uniform  product 
the  fermentation  must  be  controlled,  and  to  do  this,  a 
pure  culture  of  lactic-acid  bacteria  is  important.  These 
cultures,  or  "  starters  "  as  they  are  commonly  called,  are 
used  extensively  in  butter  and  cheese  making,  and  may  be 
secured  from  various  manufacturers.  Directions  for  their 
use  accompany  each  package,  or  may  be  found  in  the 
various  texts  on  butter  and  cheese  making. 

A  better  control  of  the  fermentation  can  be  secured  by 
using  pasteurized  milk  than  by  using  raw  milk,  but  in 
either  case  a  good  starter  should  be  used  to  insure  a  uni- 
form and  desirable  flavor  in  the  cheese. 

Souring  the  Milk.  —  The  common  method  of  making 
cottage  cheese  is  to  sour  the  skim  milk  by  a  lactic  acid 
fermentation,  rather  than  by  the  addition  of  commercial 
acid.  The  fermentation  of  the  skim  milk  may  be  carried 
on  in  milk  cans  or  in  a  vat,  depending  upon  the  quantity. 
The  milk  is  warmed  to  about  70°  F.,  and  sufficient  starter 
added  to  insure  the  coagulation  of  the  milk  at  the  desired 
time.  If  the  milk  is  pasteurized,  a  small  percentage  of 
starter  is  sufficient;  but  with  raw  milk,  a  larger  percentage, 
20  to  25  per  cent,  of  starter,  will  be  better  able  to  over- 
come any  undesirable  ferments  that  may  be  present.  This 
will  cause  the  milk  to  curdle  in  a  much  shorter  time. 

When  a  firm  curd  has  been  formed  it  is  broken  up  by 
cutting  with  cheese  knives  or  stirring  with  a  common 
stirring  rod. 


COTTAGE   CHEESE  205 

Heating  the  Curd.  —  This  is  a  very  important  process 
and  must  be  done  carefully.  Heat  is  applied  gradually, 
and  the  curd  stirred  continually,  but  gently,  until  a  tem- 
perature of  96°  to  100°  F.  is  reached,  which  should  require 
about  thirty  minutes  for  a  large  vat.  This  temperature 
is  maintained  for  about  twenty  minutes,  or  until  the  curd 
feels  fairly  firm  and  the  whey  appears  clear. 

Different  conditions  require  different  temperatures. 
Too  low  temperatures  produce  a  soft  pasty  cheese  that 
drains  with  difficulty,  and  soon  develops  a  high  acid  flavor. 
Too  high  temperatures  produce  a  dry,  granular  and  corky 
cheese,  for  which  there  is  slight  demand. 

Draining  the  Curd.  —  The  common  method  of  drain- 
ing a  small  quantity  of  curd  is  to  put  it  into  a  cheese-cloth 
bag,  and  hang  it  up  until  all  the  free  whey  has  run  out. 
For  large  quantities,  a  fine  strainer  is  more  satisfactory. 
This  may  be  of  perforated  tinware,  or  a  frame  or  box  with 
a  bottom  made  of  small  meshed  wire  netting.  A  piece  of 
cheese  cloth  is  placed  in  the  bottom  of  the  strainer  and 
the  curd  poured  upon  it.  Most  of  the  whey  quickly  runs 
through  the  cloth.  But  in  order  to  permit  the  curd  to 
drain  thoroughly,  it  is  left  on  the  strainer  with  occasional 
stirring  for  about  five  hours,  or  until  whey  ceases  to  run  off. 

Seasoning  the  Curd.  —  When  the  curd  is  taken  from 
the  strainer,  it  is  in  a  single  mass.  This  should  be 
thoroughly  broken  up  with  a  wooden  masher  or  with  the 
hands.  At  this  time  salt  is  added  in  the  proportion  of 
about  one  ounce  to  five  pounds  of  curd.  If  a  rich  cheese 
is  desired,  cream  or  butter  may  be  added.  Too  much  salt 
causes  a  dry,  granular  cheese.  In  some  instances  cumin 
or  caraway  seeds  are  added. 

Yield  of  Cheese.  —  The  yield  of  cottage  cheese  varies 
somewhat,  depending  upon  its  moisture  content,  the  per 


206  DAIRY  TECHNOLOGY 

cent  of  casein  in  the  milk  and  the  amount  of  curd  lost  in 
the  whey.  On  an  average,  seven  pounds  of  skim  milk 
produce  one  pound  of  cottage  cheese. 

For  retailing  this  product,  the  common  ice-cream  pail 
has  been  found  to  be  a  convenient  package.  It  is  cheap, 
sanitary  and  attractive.  The  package  may  be  marked 
on  the  outside  to  describe  suitably  its  contents.  These 
small  packages  are  not  sealed  air-tight.  For  this  reason 
the  cheese  should  not  be  put  into  the  retail  packages  sooner 
than  necessary.  Cottage  cheese  may  be  kept  in  larger 
bulks  in  earthen  jars.  Cottage  cheese  to  be  most  pala- 
table should  be  made  every  other  day. 

Use  of  Rennet  in  Cottage-cheese  Making.  —  This 
product  may  be  made  by  curdling  the  milk  with  rennet 
instead  of  with  the  natural  acid.  However,  in  order  to 
have  the  proper  flavor,  the  milk  should  have  an  acidity 
of  at  least  T37  per  cent  when  the  rennet  is  added.  The 
proportions  used  are  i  ounce  of  rennet  to  1000  pounds  of 
milk.  Having  curdled  the  milk,  the  rest  of  the  operation 
is  the  same  as  described  above.  Cheese  made  in  this 
way  is  apt  to  be  a  trifle  dry  and  rubber-like,  and  mild 
in  flavor. 

Use  of  Hydrochloric  Acid.  —  Much  time  can  be  saved 
by  adding  acid  direct  to  fresh  milk  instead  of  waiting 
for  it  to  be  developed  by  fermentation.  The  milk  is 
heated  to  from  70°  to  80°  F.  Hydrochloric  acid  (sp.  gr. 
i. 20)  is  added  at  the  rate  of  10  ounces  to  100  pounds  of 
milk.  This  acid  is  diluted  with  ten  times  its  bulk  of  water, 
and  added  gradually,  the  milk  being  stirred  constantly. 
The  stirring  is  continued  until  the  curd  fully  separates, 
leaving  a  clear  whey.  Then  the  whey  is  drained  from 
the  curd  and  the  process  completed  as  described  above. 
Acid  used  should  be  chemically  pure,  not  the  commercial. 


COTTAGE   CHEESE  207 

Such  cheese  lacks  the  peculiar  characteristic  flavor  of 
that  made  by  lactic  fermentation,  but  this  can  in  a  meas- 
ure be  restored  by  the  addition  of  sour  cream. 

The  average  composition  of  cottage  cheese  is  as  follows:1 

Per  cent. 

Water 73.1 

Fat 2.8 

Nitrogenous  Matter 19.8 

Non-nitrogenous  Matter 2.2 

Ash 2.1 

BUTTERMILK  CHEESE. 

In  past  years  buttermilk  was  hardly  considered  an 
asset  in  a  creamery;  but  by  the  manufacture  of  butter- 
milk cheese,  this  by-product  of  butter  making  may  be 
made  a  source  of  considerable  income. 

Heating  the  Buttermilk.  —  As  the  buttermilk  comes 
from  the  churn  it  is  run  into  a  jacketed  vat  or  can,  heated 
to  80°  F.  and  allowed  to  stand  undisturbed  for  an  hour.2 
During  this  time  the  buttermilk  coagulates,  forming  a 
soft,  flocculent  curd. 

The  contents  of  the  vat  are  then  heated,  with  slight 
stirring,  to  from  130°  to  140°  F.,  and  again  allowed  to 
stand  undisturbed  for  an  hour.  It  should  be  kept  close 
to  this  temperature  until  placed  on  the  draining  rack, 
since  the  curd  drains  faster  if  warm,  but  it  should  not 
be  re-heated  or  stirred  again  before  draining. 

In  one  large  creamery  where  all  the  buttermilk  is  manu- 
factured into  cheese,  the  buttermilk  is  placed  in  a  jacketed 
vat  and  gradually  heated  to  about  120°  F.  This  heating 
period  extends  over  a  period  of  between  2  and  3  hours. 
The  buttermilk  is  gently  stirred  at  intervals.  At  the  end 

1  Flieschman  —  The  Book  of  the  Dairy. 

2  Bui.  No.  211.     Wisconsin. 


208  DAIRY  TECHNOLOGY 

of  this  period  the  curd  has  settled  and  the  whey  is  drained 
off  from  the  top  through  gate  valves  at  different  heights 
at  the  end  of  the  vat. 

Draining  the  Curd.  —  The  vat  having  stood  at  a  tem- 
perature of  130°  to  140°  F.  for  about  an  hour,  the  curd 
will  have  gathered  at  the  bottom  of  the  whey.  The  next 
step  is  to  transfer  this  curd  with  as  little  whey  as  possible 
to  a  draining  rack  or  strainer,  such  as  is  used  in  cottage- 
cheese  making. 

If  the  curd  is  floating,  the  whey  may  be  drawn  out 
through  the  vat  gate,  being  passed  through  the  strainer 
to  catch  the  particles  of  curd  it  may  contain.  If  the  curd 
is  at  the  bottom  of  the  vat  then  most  of  the  whey  may 
be  drawn  off  through  a  siphon  and  the  thick  mass  in  the 
bottom  finally  run  out  into  the  cloth.  Thus,  most  of  the 
whey  may  be  run  off,  and  the  curd  may  be  put  upon 
the  draining  rack  as  a  thick  mush.  If  the  curd  and  whey 
are  run  into  the  strainer  together,  much  of  the  curd  will 
pass  through  the  cloth  with  the  whey. 

In  either  case,  as  soon  as  all  the  curd  is  on  the  draining 
rack,  it  is  covered  and  left  undisturbed  for  about  twelve 
hours  to  drain. 

It  is  very  important  to  have  a  uniform  consistency. 
It  will  need  some  manipulation  occasionally  to  prevent 
whey  from  gathering  on  the  surface  or  in  pockets. 

The  curd  is  sufficiently  drained  when  it  can  be  removed 
from  the  rack  and  retain  its  shape. 

Seasoning  the  Curd.  —  The  curd,  being  sufficiently 
drained,  is  removed  from  the  draining  rack,  granulated 
or  mashed,  to  break  all  lumps,  then  salted  and  packed. 
Salt  is  added  in  the  same  proportion  as  in  cottage  cheese, 
one  ounce  to  about  five  pounds  of  cheese. 

Sometimes  butter  is  mixed  with  the  curd.     This  pro- 


COTTAGE   CHEESE  209 

duces  a  richer  cheese,  and  at  times  it  is  sold  as  Neufscha- 
tel  cheese. 

The  yield  of  cheese,  the  method  of  marketing,  the  market 
value,  etc.,  are  practically  the  same  as  for  cottage  cheese. 

The  main  difference  in  the  characteristics  of  these  two 
products  is  that  the  buttermilk  cheese  has  a  smoother 
texture  than  the  cottage  cheese. 

Kind  of  Buttermilk.  —  The  cheese  made  from  butter- 
milk coming  from  old,  stale,  off-flavored  cream  will  retain 
those  undesirable  qualities.  None  but  the  best  quality  of 
buttermilk  should  ever  be  used. 

Sweet  buttermilk,  or  buttermilk  having  a  very  low  acid 
content,  will  not  curdle  on  heating;  at  least  a  longer  time 
is  required  for  coagulation.  In  making  cheese  from  such 
buttermilk  a  temperature  of  between  80°  F.  and  100°  F. 
should  be  maintained  longer.  This  will  permit  of  the 
development  of  the  lactic-acid-producing  bacteria,  and 
thereby  bring  about  proper  coagulation. 

Pasteurization  of  the  cream  does  not  materially  affect 
the  quality  of  buttermilk  cheese.  However,  cream  con- 
taining more  than  0.4  per  cent  of  acid  is  likely  to  curdle 
in  very  fine  grains  in  the  pasteurizer,  and  it  is  difficult 
to  gather  these  fine  curd  particles.  Many  of  these  run 
through  the  strainer  cloth  with  the  whey  and  are  lost. 
However,  this  can  be  overcome  by  the  addition  of  some 
skim  milk  to  the  buttermilk.  The  curd  from  the  skim 
milk  apparently  acts  as  a  sort  of  a  filter. 

For  some  unexplained  reason,  buttermilk  curd  from 
cream  containing  more  than  50  per  cent  of  fat  is  very 
fine  grained  and  is  difficult  to  collect  on  the  cheese  cloth 
strainer,  as  it  runs  through  the  meshes  with  the  whey. 
This  also  may  be  overcome  by  the  addition  of  skim  milk 
to  the  buttermilk. 


210  DAIRY  TECHNOLOGY 

Emphasis  should  be  placed  upon  the  necessity  of  ob- 
serving closely  the  different  steps  in  the  processes  of  the 
manufacture  of  buttermilk  cheese.  It  does  not  admit  of 
the  variations  that  cottage  cheese  does,  because  of  the  fine 
and  almost  soluble  condition  of  the  curd. 

Buttermilk  Cream.  —  Buttermilk  cream  is  made  in  a 
manner  similar  to  that  of  making  buttermilk  cheese;  but 
by  employing  a  lower  temperature  the  final  product  has 
the  consistency  of  thick  cream  and  is  quite  smooth  and 
free  from  grains  or  lumps.  The  only  change  in  the  proc- 
ess of  manufacture  as  described  above  is  that  instead  of 
heating  to  130°  at  the  second  heating,  the  curd  is  heated 
only  to  1 00°.  Because  of  the  soft  consistency  of  this 
product  it  requires  a  longer  time  to  drain. 

It  was  found  at  the  Wisconsin  Station  that  this  prod- 
uct has  a  market  value. 


CHAPTER  XXV. 

WHEY   BUTTER. 

IN  the  manufacture  of  all  kinds  of  cheese  whey  is  a  by- 
product. It  is  commonly  returned  to  the  farmers  and  fed 
to  hogs,  but  in  some  cases  valuable  products  are  recovered 
from  it.  The  composition  of  whey  is  fairly  constant, 
except  that  the  fat  content  varies  between  wide  limits. 
The  average  composition  of  whey  is  about  as  follows: 

Per  cent. 

Water 93.0 

Sugar 5.0 

Albumen 0.7 

Fat 0.3 

Casein 0.3 

Ash 0.7 

The  largest  percentage  of  solid  matter  in  whey  is  milk 
sugar,  the  recovery  of  which  will  be  described  in  a  subse- 
quent chapter. 

The  solids  remaining  in  whey  are  sometimes  recovered 
by  heating  or  evaporating  the  water,  the  residue  being 
made  into  a  kind  of  cheese  (mysost).  The  main  constit- 
uent of  this  cheese  is  milk  sugar,  which  is  in  marked  con- 
trast to  all  our  common  varieties  of  cheese,  the  principal 
constituents  of  which  latter  are  casein  and  fat. 

The  milk  solid  in  the  whey  that  may  be  most  easily  re- 
covered is  the  fat.  In  cheddar-cheese  making  the  quantity 
of  fat  left  in  the  whey  seldom  exceeds  0.3  per  cent,  and  may 
be  only  one-third  this  much.  In  the  manufacture  of  Swiss 
cheese  the  whey  contains  from  0.7  to  i  per  cent  of  fat. 


212  DAIRY  TECHNOLOGY 

Hence  it  was  in  factories  manufacturing  this  type  of 
cheese  that  whey-butter  making  originated. 

Original  Methods  of  Making  Whey  Butter.  —  Until 
within  the  present  decade,  little  attention  was  paid  to 
whey  butter.  It  was  manufactured  to  some  extent  in 
Swiss  cheese  factories,  but  the  product  was  more  like  lard 
chan  butter  and  sold  for  a  low  price. 

There  were  two  methods  of  recovering  the  fat  from  the 
whey,  the  "  cold  process"  and  the  "  hot  process." 

In  the  former  the  whey,  when  drawn  from  the  curd,  was 
run  into  vats  or  barrels  and  allowed  to  stand  for  24  hours. 
The  "cream"  was  then  skimmed  off  and  churned.  This 
method  of  skimming  is  not  very  efficient,  as  it  recovers 
but  about  two-thirds  of  the  fat.  By  this  process  the  whey 
cream  was  very  sour,  sometimes  containing  as  high  as  0.9 
per  cent  acidity.  Hence  the  resulting  butter  was  of  a 
poor  quality  and  had  very  poor  keeping  properties. 

In  the  "  hot  process"  the  sweet  whey  in  the  kettle  was 
heated  to  a  temperature  of  about  176°  F.  and  stirred  con- 
stantly for  about  half  an  hour.  Soon  after  the  stirring  had 
begun,  small,  white,  flocculent  pieces  of  cream  appeared 
on  the  surface.  When  all  the  cream  had  come  to  the  sur- 
face, it  was  skimmed  and  dipped  off  into  tubs,  and,  after 
standing  for  some  time,  a  considerable  quantity  of  whey 
was  drawn  off  through  a  hole  in  the  bottom  of  the  tub. 
Even  then  the  remaining  cream  contained  but  12  per  cent 
fat.  It  also  contained  a  quantity  of  coagulated  albumen. 

This  method  recovered  almost  as  much  of  the  fat  as 
can  be  removed  by  a  centrifugal  separator;  but  the  pro- 
longed high  temperature  is  very  injurious  to  the  body  of 
the  butter  made  from  this  cream.  This  cream  is  sweet 
and  pasteurized,  and  can  be  made  into  a  fair  quality  of 
butter  if  proper  methods  are  employed. 


WHEY  BUTTER  213 

Poor  Methods  Employed.  —  The  one  great  reason  for 
the  poor  quality  of  much  of  the  whey  butter  at  the  present 
time  as  well  as  in  the  past  is  that  the  cheese  makers  many 
times  spoil  the  butter  in  the  manufacturing  process.  The 
whey  cream  is  usually  not  properly  cooled  and  cared  for, 
but  is  left  to  cool  slowly  in  the  curing  room,  or  is  ripened 
at  a  temperature  of  90°  F.,  and  churned  at  a  tempera- 
ture as  high  as  70°  F.  The  resultant  product,  when  such 
methods  are  employed,  is  grease  rather  than  butter;  and 
because  of  the  high  temperatures  employed  it  occasionally 
contains  as  high  as  thirty-two  per  cent  water.  Some  of 
the  old  Swiss-cheese  makers  work  the  butter  by  taking  a 
couple  of  handfuls  of  it  on  a  cheese  board,  sprinkling  some 
salt  on  it,  and  kneading  it  as  dough  is  kneaded  in  bread 
making. 

Because  whey  butter  is  usually  made  on  such  a  small 
scale  and  is  a  side  line  in  a  cheese  factory,  it  is  not 
given  sufficient  attention  to  insure  a  high  grade  product. 
Many  cheese  makers  have  never  learned  the  art  of  butter 
making,  and  hence  are  not  qualified  to  turn  out  a  high  grade 
of  whey  butter. 

Modern  Whey-butter  Making.  —  That  a  very  high 
quality  of  butter  may  be  made  from  whey  cream,  has 
been  demonstrated  on  numerous  occasions.  At  Brockville 
Exhibition,  Ontario,  Canada,  in  1907,  in  the  butter  con- 
test, the  exhibit  that  carried  off  first  prize  was  whey  butter. 
This  was  in  competition  with  creamery  butter.  Whey  butter 
has  been  made  by  one  of  the  authors  and  submitted  to 
several  dairymen  for  examination.  It  could  not  by  any 
physical  test  be  distinguished  from  creamery  butter.  (This 
butter  did  not  include  drippings  from  the  milled  curd.) 

In  order  to  make  whey  butter  a  profitable  product,  the 
cheese  factory  should  have  at  least  10,000  pounds  of  milk 


214  DAIRY  TECHNOLOGY 

daily.  A  separator  is  necessary  in  order  to  secure  the  cream 
in  good  condition.  The  whey  should  be  run  through  the 
separator  while  hot,  as  soon  as  possible  after  being  drawn 
from  the  curd.  A  cream  of  not  less  than  thirty  per  cent 
fat  should  be  secured,  pasteurized  and  cooled,  ripened  with 
a  starter,  and  treated  in  every  way  the  same  as  cream  in  a 
whole-milk  creamery. 

The  butter  can  be  made  more  economically  by  gathering 
the  cream  from  several  cheese  factories  and  taking  it  to 
one  central  point  for  proper  ripening  and  churning.  But  it 
is  essential  that  each  factory  take  proper  care  of  the  cream 
and  deliver  it  in  a  sweet,  clean  condition. 

The  skimming  of  whey  is  practiced  commonly  in  fac- 
tories making  cheddar  or  American  cheese,  as  well  as  in 
Swiss-cheese  factories.  Some  authorities  claim  that  ched- 
dar cheese  when  made  under  most  favorable  conditions 
leaves  so  little  fat  in  the  whey  that  the  cost  of  recovering 
it  would  hardly  be  met  by  the  value  of  the  fat  secured. 
When  the  cheese  maker  is  deriving  direct  profit  from  the 
whey  cream,  he  may  so  handle  the  curd  while  in  the  whey 
that  a  very  considerable  portion  of  the  fat  that  should  go 
into  the  cheese  is  left  in  the  whey  to  be  recovered  by  the 
separator. 

Disposal  of  Whey  Butter.  —  It  is  very  evident  that  whey 
butter  must  be  so  branded  as  to  distinguish  it  from  creamery 
butter.  So  much  whey  butter  is  of  poor  quality  that  this 
product,  no  matter  how  good  it  is,  brings  a  lower  price 
on  the  market  than  does  creamery  butter.  To  some  ex- 
tent the  local  patrons  of  the  cheese  factory  may,  however, 
use  the  whey  butter.  This  latter  is  of  the  same  value  to 
them  as  a  similar  grade  of  creamery  butter.  However, 
if  whey  butter  of  high  quality  be  offered  on  the  market 
for  some  time,  it  will  soon  gain  a  favorable  reputation 


WHEY  BUTTER  215 

and  be  able  to  compete  with  butter  made  from  natural 
cream. 

Profits  from  Whey-butter  Making.  —  Each  succeed- 
ing year  shows  an  increase  in  the  volume  of  whey  butter 
manufactured.  Last  year  (1910)  Lafayette  County,  Wis- 
consin, alone,  produced  84,000  pounds  of  this  product. 
The  various  separator  companies  have  constructed  sepa- 
rators especially  adapted  to  the  separation  of  whey. 

A  cheese  factory  receiving,  on  an  average,  6000  pounds 
of  milk  per  day  would  handle  2,190,000  pounds  of  milk  per 
year.  On  a  basis  of  3  pounds  of  whey  butter  from  each 
thousand  pounds  of  milk  made  into  cheese,  6570  pounds 
of  butter  would  be  made  in  one  year.  If  this  butter  is 
properly  made  it  should  sell  for  an  average  price  of  25  cents 
per  pound.  The  income  from  this  butter  would  be 
$1642.25. 

In  many  places  one  half  the  gross  income  from  whey 
butter  is  divided  among  the  patrons.  This  would  leave 
$821.125  as  the  cheese  factory's  share.  From  this  must 
be  deducted  about  $500,  which  includes  the  interest  on 
the  extra  investment,  depreciation  in  value  and  the  charge 
for  labor  and  fuel.  The  net  profit  to  the  cheese  factory 
would  amount  to  about  $321.25  for  the  year. 


CHAPTER  XXVI. 

MILK  SUGAR. 

MILK  SUGAR  or  lactose  (C^H^On  +  H2O)  is  probably 
found  in  the  milk  of  most  mammals,  and,  so  far  as  known, 
is  found  nowhere  else  in  nature.  Richmond  has  shown 
that  the  milk  of  the  goat,  the  ass  and  the  Egyptian 
gamoose  or  water-buffalo  contain  lactose.  Richmond  and 
Pappel  also  found  that  the  sugar  in  the  milk  of  the 
gamoose  in  winter  differed  from  lactose.  This  sugar  they 
called  "Tawfikose."  Sugar  of  mares'  milk  has  the  prop- 
erty of  easily  undergoing  alcoholic  fermentation,  a  property 
not  possessed  by  lactose  from  cows'  milk.  According  to 
Richmond  and  Pappel,  sugar  of  human  milk  is  not  identical 
with  that  of  cows'  milk.  The  milk  sugar  of  commerce 
is  derived  from  cows'  milk  of  which  it  forms  about  five 
per  cent.  It  is  but  slightly  sweet,  hardly  a  hundredth  as 
sweet  as  cane  sugar. 

This  product  is  used  in  modifying  milk  for  feeding  in- 
fants and  invalids,  as  a  diluent  in  various  strong  drugs, 
in  the  preparation  of  medicinal  powders,  and  in  the  manu- 
facture of  pentanitro-lactose,  which  forms  a  part  of  some 
high  explosives. 

History  and  Development  of  Milk-sugar  Manufac- 
turing. —  Milk  sugar  is  said  to  have  been  discovered  by 
accident  early  in  the  eighteenth  century  by  a  peasant 
in  Switzerland  who  was  making  cheese.  The  cheese 
having  been  hung  up  in  a  bag  to  drain  for  some  time, 
this  observing  Swiss  noticed  a  few  crystals  that  had  been 

216 


MILK  SUGAR  217 

formed  by  the  evaporation  of  the  whey.  A  druggist, 
to  whom  these  crystals  were  shown,  predicted  that,  if 
the  product  could  be  manufactured  in  quantities,  it  would 
become  an  important  article  of  commerce.  In  the  first 
half  of  the  nineteenth  century,  milk  sugar  was  being  manu- 
factured by  very  crude  methods  in  Switzerland,  Holland 
and  Germany.  The  sugaring  processes  occupied  about 
fourteen  days  and  the  product  then  contained  many  im- 
purities. But  there  was  great  demand  for  even  this 
impure  product  and  the  industry  grew.  Switzerland  con- 
trolled the  milk  sugar  industry,  and  supplied  the  markets 
of  the  world.  In  time  the  United  States  became  the  chief 
customer  of  Switzerland,  taking  about  three-fourths  of  the 
$60,000  worth  annually  exported  from  that  country.1 

The  first  attempt  to  manufacture  milk  sugar  in  this 
country  was  made  in  1881  by  Dr.  Gerber.  He  worked 
for  about  two  years  in  Little  Falls,  N.  Y.,  and  then  gave 
it  up,  declaring  that,  on  account  of  the  poor  quality  of 
milk  produced  in  the  United  States,  Switzerland  need 
never  fear  competition  in  the  milk-sugar  industry  from 
that  source. 

However,  by  1890  the  milk-sugar  industry  was  fairly 
well  established  in  this  country  and  was  developing 
rapidly.  American  improvements  in  the  process  of  pro- 
duction have  made  possible  a  product  of  much  higher 
purity  than  the  sugar  formerly  imported  from  Switzerland. 
To-day  milk  sugar  is  exported  from  this  country  to  Europe 
and  has  to  a  considerable  extent  replaced  the  Swiss  product. 

Milk-sugar  Making  in  the  United  States.  —  Alvord,  in 

1897,  reported  four  or  five  milk  sugar  factories  in  Illinois, 

New  York  and  Ohio,  using  whey  from  neighboring  cheese 

factories,  for  which  they  paid  from  4  to  7  cents  per  hun- 

1  Alvord  in  United  States  Dept.  of  Agriculture  Yearbook,  1897. 


2l8  DAIRY  TECHNOLOGY 

dred  pounds.  The  largest  factory  of  this  kind  in  the 
world  is  located  in  Illinois  and  has  a  capacity  of  one  and 
a  half  tons  of  milk  sugar  per  day.  They  get  on  an  average 
3.4  pounds  of  sugar  from  100  pounds  of  whey.  At  this 
factory  the  whey  from  casein  making  as  well  as  the  whey 
from  cheese  factories  is  used,  the  sugar  from  the  former 
source  being  of  just  as  high  quality  as  that  from  the  latter. 

The  Process  of  Manufacture.  —  Whey,  acidified  to 
about  one  per  cent  of  hydrochloric  acid,  is  heated  in  large 
vats  to  the  boiling-point  with  steam.  This  precipitates 
the  albumen.  The  solution  is  then  made  neutral  with 
calcium  hydroxide,  evaporated  in  a  vacuum  pan  to  a 
syrupy  consistency  (22°  to  25°  Baume),  and  filtered 
through  a  series  of  cloths  in  a  high-pressure  filter  press. 
When  sufficient  syrup  has  accumulated,  it  is  again  run 
into  the  vacuum  pan  and  evaporated,  at  about  no°F., 
to  a  much  richer  syrup.  This  latter  is  drawn  out  into 
shallow  boxes,  where  it  cools  and  crystallizes,  in  24  to  48 
hours,  into  what  appears  to  be  a  yellow  sand.  This  is 
crude  sugar,  and  must  be  passed  through  several  proc- 
esses of  purification. 

This  mass  is  first  washed  with  cold  water  in  a  centrifuge. 
The  centrifuge  is  a  combination  of  drums  with  perforated 
walls  and  fine  sieves.  The  syrup  is  thrown  out  through 
the  sieves  and  the  sugar  crystals  are  retained  within 
them.  The  crystals  are  here  washed  with  cold  water 
to  remove  calcium  chloride  and  other  soluble  impurities. 
The  washings  and  the  syrup  thrown  out  by  the  centri- 
fuge are  saved  and  the  contained  sugar  recovered.  The 
sugar  crystals  are  redissolved  in  hot  water,  certain  chem- 
icals are  added  and  the  solution  is  allowed  to  stand  over 
night.  In  the  morning  the  clear  liquid  is  siphoned  off. 
The  settlings  in  the  bottom  of  the  tank  are  filtered  and 


MILK   SUGAR  2IQ 

the  filtrate  is  added  to  the  solution  previously  siphoned 
off. 

This  is  then  heated  to  about  170°  F.,  and  filtered  through 
bone  black  to  remove  coloring  matter  and  other  impuri- 
ties. This  filtered  solution  is  now  condensed  to  the 
proper  point  in  a  vacuum  pan.  The  resulting  pasty  mass 
is  passed  through  the  centrifuge  and  washed,  and  put 
upon  tray  frames  with  cloth  stretched  over  them  to  dry. 
These  trays  are  placed  upon  racks  in  a  drying  room  and 
the  sugar  dried  at  60°  C.  (140°  F.).  When  dry  it  is  pow- 
dered in  a  ball  mill  and  bolted  in  a  manner  similar  to  that 
of  bolting  flour  in  a  flour  mill.  The  product  is  a  fine 
white  powder,  and  is  put  into  barrels  holding  about  two 
hundred  pounds  for  shipment. 

By-Products  of  Milk-sugar  Making.  —  The  raw  mate- 
rial used  in  the  manufacture  of  milk  sugar  is  a  by-product 
of  another  industry,  yet  the  sugar  industry  itself  pro- 
duces a  by-product.  This  is  the  proteid  matter,  mainly 
albumen,  that  is  taken  from  the  filter  press.  This  proteid 
matter  is  placed  on  cloth  racks,  kiln  dried,  and  sold  as  food 
for  poultry  and  stock. 

Alvord  reports  the  use  of  milk-sugar-factory  by-prod- 
ucts for  pig  feeding.  Young  pigs  just  weaned  were 
bought  and  fed  on  nothing  but  waste  from  the  sugar  fac- 
tory. They  thrived  and  fattened  so  that  they  were  ready 
to  kill  at  six  to  seven  months  of  age.  This  feed  is  highly 
nitrogenous,  and  evidently  a  very  narrow  ration.  It 
seems  probable  that  even  better  results  would  be  secured 
by  using  a  highly  carbonaceous  food  in  combination  with 
the  sugar-factory  waste. 

Mysost.  —  Instead  of  using  the  whey  from  cheese  fac- 
tories for  the  manufacture  of  milk  sugar,  it  may  be  con- 
verted into  a  kind  of  cheese  known  as  Mysost.  Although 


220  DAIRY  TECHNOLOGY 

made  in  this  country  to  some  extent,  this  cheese  is  more 
especially  a  product  of  cheeseries  in  Norway,  Sweden  and 
Denmark.  It  has  a  yellowish-brown  color,  the  consistency 
of  firm  butter,  and  a  sweet,  characteristic  flavor  similar  to 
a  concentrated  evaporated  milk  flavor.  In  this  country 
it  is  marketed  in  paraffined  pound  cubes,  or  in  cylindrical 
shapes,  wrapped  in  tinfoil. 
The  method  of  manufacture  is  as  follows:1 

"  As  soon  as  the  curd  of  the  regular  cheese  is  removed 
from  the  whey,  the  whey  is  strained  and  is  put  in  a  kettle 
or  large  pan  over  the  fire  and  the  albuminous  material 
which  rises  to  the  surface  is  skimmed  off.  The  whey 
is  evaporated  as  rapidly  as  possible  with  constant  and 
thorough  stirring.  When  it  has  reached  about  one- 
fourth  its  original  volume  the  albumin  previously  skimmed 
off  is  returned  and  stirred  thoroughly  to  break  up  all  possi- 
ble lumps.  When  the  whey  has  attained  the  consistency 
of  thickened  milk  it  is  poured  quickly  into  a  wooden  trough 
and  stirred  with  a  paddle  until  cool  to  prevent  the  forma- 
tion of  sugar  crystals.  This  can  then  be  molded  into  the 
desired  form." 

Its  composition,  according  to  Dahl,  is:  Water,  23.57 
per  cent;  Fat,  16.26  per  cent;  Proteids,  8.88  per  cent; 
Milk  sugar,  Lactic  acid,  etc.,  44.84  per  cent;  Ash,  4.76 

per  cent. 

1  Bu.  An.  Ind.,  Bui.  105. 


CHAPTER  XXVII. 

CASEIN. 

THE  separation  of  casein  from  milk  for  cheese-making 
purposes  has  been  practiced  for  over  two  thousand  years, 
but  only  during  the  last  few  decades  has  scientific  research 
revealed  the  multitude  of  uses  to  which  this  product  may 
be  put  in  the  technical  industries.  Casein  to-day  is  manu- 
factured on  a  large  scale  and  used  in  the  preparation  of 
paint,  glue,  paper,  dress  goods,  as  imitation  ivory,  horn, 
etc.,  and  as  a  concentrated  foodstuff. 

Casein  exists  in  milk  not  in  true  solution,  but  in  sus- 
pension. It  may  be  separated  out  by  the  following  means : 
(i)  filtration  through  a  porous  clay  filter,  (2)  centrifugaliz- 
mg?  (3)  precipitation  by  dilute  acids,  (4)  precipitation  by 
ferments,  and  (5)  precipitation  by  salts.  Casein,  when 
dried,  forms  a  horny  mass  insoluble  in  water  or  dilute  acids, 
but  soluble  in  alkalis  and  concentrated  acids. 

Statistics  show  that  the  use  of  dry  casein  has  increased 
100  per  cent  during  the  last  five  years,  and  that  Germany 
consumes  about  four  thousand  tons  annually.  The  entire 
consumption  in  Europe  and  America  is  placed  at  about 
fifteen  thousand  tons.  The  United  States  Census  of  1909 
places  the  casein  production  in  this  country  at  almost 
seven  thousand  tons,  an  increase  of  12  per  cent  in  five 
years. 

Preparation  of  Casein.  —  In  the  chemical  laboratory, 
casein  is  prepared  by  diluting  the  milk  to  about  five  times 
its  volume,  and  adding  sufficient  acetic  acid  to  make  the 

221 


222  DAIRY  TECHNOLOGY 

acidity  of  the  solution  one  tenth  per  cent.  This  causes 
the  precipitation  of  the  casein.  It  is  then  filtered  and 
washed  well  with  distilled  water.  This  latter  will  dissolve 
out  the  acid  and  sugar  in  the  residue.  This  residue  on 
the  filter  is  dried  and  redissolved  in  the  least  possible 
amount  of  ammonia,  and  upon  standing  awhile,  the  fat 
will  rise  to  the  top.  The  liquid  can  then  be  siphoned  off 
and  filtered.  The  filtrate  is  again  precipitated  by  acetic 
acid.  This  precipitate  is  redissolved  in  ammonia  and  the 
process  is  repeated  three  or  four  times  until  it  is  pure  and 
white.  This  casein  is  now  rubbed  in  a  mortar  with  80  per 
cent  alcohol  and  the  alcohol  poured  off.  This  treatment 
with  alcohol  is  repeated  several  times,  absolute  alcohol 
being  used  the  last  time.  This  is  followed  by  treatment 
with  ether  until  all  the  alcohol  is  removed.  The  product  is 
pure  casein  which,  when  thoroughly  dried,  is  in  a  powdery 
condition.  However,  the  preparation  of  casein  for  com- 
mercial purposes  is  quite  a  different  process. 

Commercial  casein  is  prepared  from  skim  milk  on  quite 
a  large  scale,  usually  in  a  room  or  building  adjoining  a 
large  whole-milk  creamery. 

Five  thousand  or  more  pounds  of  skim  milk  are  placed 
in  a  jacketed  vat  and  heated  to  about  130°  F.  Then 
sufficient  acid  is  added  to  precipitate  the  casein.  In  some 
cases  commercial  sulphuric  acid  is  used  in  the  proportion 
of  one  pint  of  acid  diluted  in  water  to  one  thousand  pounds 
of  milk.  At  other  factories  the  kind  and  quantity  of  acid 
used  are  considered  trade  secrets.  The  curdling  should 
take  place  under  proper  conditions.  If  an  excess  of  sul- 
phuric acid  or  too  strong  acid  is  used,  the  curd  will  be 
discolored. 

When  the  milk  has  been  coagulated,  the  whey  separates 
and  is  drawn  off.  To  facilitate  and  hasten  this  process, 


CASEIN  223 

the  curd  is  broken  into  small  chunks  and  piled  on  a  drain- 
ing table  or  rack  covered  with  coarse  cloth.  Here  the 
whey  and  acid  are  washed  out  by  streams  of  cold  water. 
The  curd  is  then  allowed  to  drain  for  two  or  more  hours 
until  it  becomes  dry  enough  to  be  ground.  Or  it  may  be 
placed  in  a  press  similar  to  an  upright  cheese  press  and 
left  there  over  night.  The  next  morning  the  curd  is  passed 
through  a  curd  mill,  such  as  is  used  in  the  manufacture 
of  cheddar  cheese,  and  ground  into  small  pieces. 

The  curd  is  then  placed  upon  drying  trays,  which  con- 
sist of  coarse  cloth  stretched  over  a  wooden  frame.  These 
trays  of  curd  are  placed  in  the  drier  and  left  there  until 
the  pieces  of  curd  are  quite  dry  and  horny.  The  drier 
may  be  either  of  the  horizontal  or  vertical  type.  In  both 
cases  it  consists  of  a  heated  space  in  which  the  trays  are 
placed  in  tiers.  At  one  end,  or  at  the  bottom  of  the  drier, 
is  a  power-driven  fan  that  forces  a  current  of  air  over  a 
hot  radiator  and  thence  to  the  trays  of  curd.  A  tempera- 
ture of  about  120°  F.  is  maintained  for  ,about  twenty- 
four  hours. 

At  the  end  of  this  time  the  curd  is  dry  and  is. taken 
from  the  trays,  put  into  sacks  holding  about  one  hundred 
pounds  each,  and  shipped.  At  this  stage  the  curd  is  in 
small,  yellowish  white,  irregular  lumps.  If  the  curd  is 
not  thoroughly  washed  before  drying,  the  presence  of  milk 
sugar  and  heat  will  cause  a  discoloration  and  a  flinty 
appearance  of  the  curd.  This  greatly  lessens  its  solu- 
bility and  commercial  value. 

One  hundred  pounds  of  skim  milk  will  yield  about  3^ 
pounds  dried  casein,  which  contains  about  twelve  per 
cent  of  moisture.  For  this  dry  curd  the  casein  companies 
pay  about  seven  cents  per  pound,  which  is  equivalent  to 
24.5  cents  per  100  pounds  of  skim  milk. 


224  DAIRY  TECHNOLOGY 

According  to  the  Union  Casein  Company  the  following 
equipment  is  needed  for  the  manufacture  of  casein  from 
skim  milk: 

"  The  machinery  is  not  expensive;  it  consists  of  a  skim- 
milk  vat,  unlined ;  a  press,  one  curd  mill  and  wooden  drying 
closet.  The  kiln  covers  a  space  of  about  four  feet  high, 
twenty-two  feet  long  and  six  feet  wide,  built  along  the  wall  of 
(preferably)  the  second  floor.  This  size  is  suitable  for  drying 
curd  or  casein  from  24,000  pounds  of  skim  milk.  (A  larger 
or  smaller  size  can  be  made  proportionately.)  The  radiator 
and  ball-bearing  fan  are  the  principal  parts  required  for  the 
making  of  the  drier.  Radiator  costs  $48.00;  fan  $35.00.  In 
addition  to  the  dryer  you  will  require  12  trucks,  .each  of 
which  holds  30  wire  trays.  One  truck  and  one  set  of  trays  are 
required  for  drying  the  wet  curd  extracted  from  2000  pounds 
of  skim  milk.  The  trucks  cost  $2.50  each  and  the  trays  $9.00 
per  dozen.  The  curd  flaking  machine  costs  $55.00;  press 
$35.00.  One  press  is  required  for  each  12,000  pounds  of 
milk." 

This  commercial  casein  must  be  purified  if  intended  for 
certain  technical  uses.  To  accomplish  this  the  casein  is 
macerated,  and  dissolved  in  dilute  alkali  at  a  high  temper- 
ature, cooled,  reprecipitated  with  an  acid,  drained  and 
washed  repeatedly  with  water,  and  finally  pressed  and  dried. 

Casein  from  Buttermilk.  —  The  large  central  creamery 
plants  of  to-day  are  taking  up  side  lines,  and  manufacturing 
several  by-products.  One  of  these  is  casein  from  butter- 
milk. 

The  process  of  recovering  casein  from  buttermilk  is 
similar  to  that  of  recovering  casein  from  skim  milk.  But 
the  physical  and  chemical  condition  of  the  buttermilk  casein 
necessitates  certain  modifications.  At  different  factories 
slightly  different  methods  are  used,  but  in  a  general  way  the 
processes  are  the  same. 


CASEIN  225 

The  buttermilk,  when  drawn  from  the  churn,  is  pumped 
into  large  vats  or  tanks,  steam  is  turned  directly  into  the 
buttermilk,  and  the  temperature  is  brought  to  about  160°  F. 
The  hot  buttermilk  is  left  undisturbed  for  several  hours, 
or  over  night.  It  is  then  run  over  a  cooler  into  a  smaller 
vat,  for  convenience  in  handling,  and  the  temperature 
brought  to  about  100°  F.  Sulphuric  acid  is  added  in  the 
proportion  of  about  six  quarts  of  acid  to  300  gallons  of 
buttermilk.  The  proportion  is  varied  with  the  season  of 
the  year,  the  acidity  and  the  condition  of  the  buttermilk. 
An  excess  of  acid  will  produce  a  dark-colored  casein  that 
has  a  low  market  value.  Insufficient  acid  causes  incom- 
plete gathering  of  the  curd;  hence,  many  small  particles 
are  lost  in  the  whey.  Within  one  hour  from  the  time  the 
acid  is  added  the  whey  may  be  readily  drawn  off  and  the 
curd  put  to  press.  The  pressing,  grinding  and  drying  of 
the  curd  is  carried  on  in  a  manner  similar  to  that  of  han- 
dling curd  from  skim  milk. 

Casein  from  buttermilk  differs  from  casein  from  skim 
milk  in  the  following  particulars: 

Buttermilk  casein  is  darker  in  color,  contains  a  higher 
percentage  of  fat,  is  less  soluble,  and  cannot  be  used  so 
extensively  nor  for  such  high-grade  products  as  can  skim- 
milk  casein.  The  former  has  a  market  value  from  ten  to 
sixty  per  cent  .lower  than  that  of  the  best-grade  skim  milk 
casein. 

Casein  Glue.  —  The  crude  casein  may  be  converted  into 
a  glue  by  the  following  simple  process:  To  the  casein  add 
one-fourth  of  its  weight  of  distilled  water  and  one  to  four 
per  cent  of  bicarbonate  of  soda.  Mix  thoroughly,  then  add 
a  quantity  of  distilled  water  equal  to  the  original  amount 
used,  to  complete  the  solution,  and  let  it  stand  from  five 
to  six  hours.  At  the  end  of  this  time  the  glue  will  be 


226  DAIRY  TECHNOLOGY 

ready  for  use.  An  antiseptic  should  be  added  to  prevent 
fermentation. 

There  are  many  patented  formulas  for  the  manufac- 
ture of  casein  glue.  Borax,  ammonia,  lime,  and  various 
alkaline  salts  are  used  in  this  connection  singly  or  in  com- 
bination. 

Closely  allied  to  the  casein  glues  and  of  similar  composi- 
tion are  several  kinds  of  casein  putties  and  stopping. 
These  materials  are  employed  in  wood  working  and  cabinet 
making. 

Casein  Paints.  —  It  has  long  been  recognized  that  the 
addition  of  milk  to  whitewash  increases  its  adhesiveness 
and  durability.  This  result  is  principally  due  to  a  combina- 
tion of  the  casein  and  lime.  This  compound,  formed  by  the 
combination  of  casein  with  certain  other  substances,  forms 
the  basis  of  all  the  numerous  casein  paints  of  to-day. 

Scherer  gives  the  following  formula  for  a  paint  for  out- 
side work: 

100  parts  by  weight  of  casein,  soluble  in  alkali. 
100     "       "        "       "  caustic  lime  from  marble. 
800     "       •'        "       "  levigated  chalk. 
2  to  2 \     "       "        "       "  ultramarine  (for  white  only), 
i  part    "        "       "  borax. 

On  the  market  to-day  are  casein  paints  of  all  kinds 
and  colors,  liquid  and  powder,  some  of  which  are:  Casein 
Enamel  Paint,  Kalsomine  Wash,  Quick-Drying  Casein 
Paint,  Cold  Water  Paint,  Boiled  Oil  Substitute,  Water- 
proof Paint  for  Playing  Cards,  Casein  Cement  Paint,  etc. 
Similar  paints  are  prepared  by  the  use  of  the  whole  milk 
instead  of  merely  the  casein  constituent. 

Milk-cement  Paint.  —  A  most  effective  and  durable 
paint  can  be  made  from  milk  and  cement  by  mixing  one 
gallon  of  milk  and  about  four  pounds  of  Portland  cement, 


CASEIN  227 

adding  sufficient  Venetian-red  paint  powder  (cost,  3  cents 
per  pound)  to  give  a  good  color.  Any  other  paint  powder 
of  a  different  color  can  be  used  as  well.  This  should  be 
stirred  thoroughly.  The  only  objection  to  this  is  that  the 
milk  will  not  hold  the  cement  in  suspension  on  account  of 
the  great  weight  of  the  cement.  It  has  to  be  thoroughly 
stirred  all  the  time  during  its  use. 

About  six  hours  after  applying,  the  coat  of  paint  will  be 
dry,  and  it  is  not  affected  by  water.  The  authors  have 
used  this  paint  with  satisfaction.  It  seems  to  petrify  the 
surface  of  the  wood,  which  is  evidently  the  reason  why  it 
is  so  preservative  in  its  effect. 

If  water  is  used  instead  of  milk,  the  paint  will  not  adhere 
so  well  to  the  wood. 

The  paint  when  mixed  with  a  little  extra  cement  is  a 
good  substance  for  painting  trees  which  have  been  injured. 
When  painted  on  the  bottom  of  the  trunk  of  trees,  it  pro- 
tects against  rabbits  gnawing  them. 

Plastic  Masses  from  Casein.1  —  "  Like  all  substances 
possessing  strong  adhesive  properties,  casein  is  specially 
adapted  for  the  preparation  of  plastic  masses,  which  can 
be  molded,  either  in  a  mixture  with  organic  substances 
like  sawdust,  wood  meal,  paper,  etc.,  or  alone  in  the  form 
of  paste  or,  a  more  or  less  dry  powder,  and  set  hard  when 
dry.  Casein  mixed  with  lime  or  other  alkaline  material 
can  be  converted,  by  the  addition  of  a  little  water,  into  a 
plastic  mass  which,  though  very  gradually,  dries  in  the  air 
to  a  transparent  mass  as  hard  as  bone,  and  can  be  stained 
any  color.  In  this  condition  it  can  be  turned  in  the  lathe 
or  worked  with  any  other  cutting  tool.  When  plastic  casein 
is  mixed  with  other  substances,  such  as  organic  or  finely 
powdered  inorganic  materials,  the  resulting  masses  are 
endowed  with  the  property  of  drying  quickly,  especially 
under  the  influence  of  warmth.  Care  must,  however,  be 

.  Scherer.  —  Casein,  Its  Preparation  and  Utilization. 


228  DAIRY  TECHNOLOGY 

taken  in  the  drying  process,  owing  to  the  fact  that  all 
masses  containing  much  water  shrink  and  easily  crack 
while  drying. 

"The  adhesive  properties  of  casein  have  already  met  with 
extensive  industrial  application.  Great  success  has  at- 
tended, for  example,  the  attempts  made  to  render  celluloid 
uninflammable  by  admixtures  of  casein;  and  special  men- 
tion will  be  made  later  of  the  newest  celluloid  substitute, 
galalith.  This  affords  an  instance  of  how  modern  ingenuity 
has  enabled  a  raw  material,  hitherto  of  but  slight  use 
technically,  to  become  of  great  industrial  utility." 

And  so  we  have  an  imitation  ivory  and  horn,  and  insu- 
lating preparation,  and  antiradiative  and  anticorrosive 
substance  for  covering  steam  and  refrigeration  pipes,  a 
covering  for  floors  that  resembles  linoleum,  imitation 
leather,  etc. 

Consul  General  O.  G.  D.  Huges  of  Coburg,  Germany, 
reports  the  following: 

"At  the  Hygienic  Milk  Supply  Exhibition  which  was 
lately  held  at  Hamburg,  the  Vereinigten  Gummiwaren- 
Fabriken,  of  Hamburg  and  Vienna,  exhibited  a  number  of 
objects  which  seemingly  had  nothing  to  do  with  the  Hy- 
gienic Milk  Supply.  There  were  shown  nicely  arranged  in 
glass  boxes,  combs,  seemingly  made  of  bone,  cigar  holders 
with  amber-colored  mouthpieces,  knives  and  forks  with 
handles  similar  in  appearance  to  ebony,  ferrules  for  um- 
brellas and  canes,  and  bells,  rings,  chess  figures,  dominoes, 
etc.,  also  a  small  table  with  an  inlaid  marble  slab,  and  finally 
a  number  of  thick  slabs  and  staves  of  every  imaginable 
variation  of  marble  colors,  but  of  considerably  less  weight 
than  marble.  These  objects  were  made  of  galalith,  or  milk 
stone." 

Manufacture  of  Galalith.  —  This  peculiar  substance 
known  as  milk  stone  is  prepared,  according  to  Scherer,  by 
the  following  method:  Casein,  prepared  by  precipitation 
with  rennet  instead  of  an  acid,  is  mixed  with  13  times  its 


CASEIN  i  229 

weight  of  water.  This  contains  in  solution  2^  parts  of 
caustic  soda  per  100  parts  of  dry  casein.  This  produces 
a  milky  liquid,  which  may  be  cleared  by  adding  a  larger 
quantity  of  5-per-cent  caustic  soda.  The  clear  solution 
is  treated  with  an  acid  to  precipitate  the  casein,  is  dried 
and  then  moistened  with  a  little  acid  to  restore  its  plas- 
ticity. To  prepare  a  hard  casein  mass  (milk  stone),  the 
casein  is  treated  with  formaldehyde,  pressed  or  molded 
into  any  desired  form.  Any  desired  coloring  matter  may 
be  added  to  the  casein  before  its  treatment  with  formalde- 
hyde, to  produce  imitation  ebony,  marble,  etc.  The  final  dry- 
ing must  proceed  very  slowly  in  order  to  prevent  cracking. 

Galalith,  in  a  general  way,  resembles  celluloid.  The 
specific  gravities  of  the  two  substances  are  about  the  same. 
Galalith  is  harder  and  less  elastic  than  celluloid;  it  is  hard 
to  cut,  and  inclined  to  chip;  it  takes  a  higher  polish  than 
the  celluloid;  it  cannot  be  made  into  so  thin  transparent 
sheets,  and  it  absorbs  some  water  when  soaked. 

Casein  in  the  Textile  Industry.  —  Casein  is  used  largely 
in  calico  printing,  and  more  rarely  in  the  finishing.  Finish 
refers  to  a  glossy  dressing  like  starch.  The  gummy  am- 
moniacal  solution  of  casein  is  employed  as  a  medium  for 
printing  and  fixing  powdered  pigments  that  will  stand 
alkali.  Fairly  well  fixed  colors  are  obtained,  when  the 
ammonia  has  been  driven  off  by  vigorous  drying  and  steam- 
ing. Casein  dissolved  in  lime  water  may  be  used  for  the 
same  purpose  as  the  ammoniacal  solution.  In  this  case 
the  colors  are  fixed  by  the  action  of  the  carbonic  acid  in 
the  air,  the  products  being  calcium  carbonate  and  insoluble 
casein. 

Following  are  some  of  the  casein  products  used  in  this 
industry:  caseo  gum,  to  assist  fibers  in  absorbing  dyestuffs; 
glutin,  a  glaze  for  dressing  certain  fabrics;  and  a  product 


230  DAIRY  TECHNOLOGY 

for  waterproofing  cloth  and  for  loading  silk   (making  it 
appear  heavier  than  it  really  is). 

Casein  Foodstuffs.  —  The  importance  of  proteids  in 
the  food  of  man  is  generally  recognized.  This  essential  is 
usually  furnished  to  a  large  extent  in  the  form  of  meat, 
but  the  proteids  of  milk  may  form  a  very  satisfactory 
substitute  for  meat,  and  there  are  on  the  market  for  this 
purpose  a  number  of  casein  products.  Lactarine,  Sanato- 
gen  and  Galactogen  are  made  up  mostly  of  casein.  Eulac- 
tol  is  an  evaporated  milk  similar  to  our  common  milk 
powder.  Plasmon,  Nutrium,  etc.,  are  products  consisting 
of  casein,  milk  sugar,  and  salts. 

Casein  in  the  Paper  Industry.  —  "An  important  part 
is  played  by  the  adhesives  in  the  industries  wherein  paper 
is  employed,  both  in  order  to  inseparably  fasten  together 
individual  sheets  of  paper,  convert  paper  pulp  into  a  mould- 
able  condition,  and  also  for  the  application  of  thin  layers 
of  colouring  matter  or  other  coatings  may  be  either  mat  or 
more  or  less  glossy,  but  in  any  event  must  be  able  to  with- 
stand to  a  certain  extent  the  influence  of  moisture.  For  all 
these  purposes  casein  is  admirably  adapted,  since  it  will 
stick  sheets  or  bands  of  paper  together  and  forms  thin 
coatings  of  considerable  elasticity  both  alone  or  in  associa- 
tion with  other  substances,  colouring  matters  in  particular. 
When  a  solution  of  casein  is  treated  with  small  quantities 
of  formaldehyde,  and  the  article  coated  with  the  prepara- 
tion exposed  to  the  air,  a  number  of  new  products  can  be 
obtained.  Thus,  for  instance  (by  patented  processes),  we 
obtain  waterproof  cardboard  boxes  and  cartridge  cases, 
washable  wall  papers,  washable  paper  garments,  coloured 
papers,  art  papers,  transfer  papers  and  so  on.  Utensils, 
more  particularly  basins,  dishes  and  the  like,  made  of  paper 
pulp  or  millboard,  can  be  rendered  waterproof  by  treat- 
ment with  formaldehyde,  and  used  for  a  variety  of  purposes, 
e.g.,  as  developing  dishes  in  photography.  Similarly,  card- 
board treated  in  the  same  way  can  be  used  for  stereo- 


CASEIN  231 

type  matrices,  and  will  keep  for  any  length  of  time,  by 
reason  of  its  lightness  and  durability.  It  is  thus  evident 
that  the  field  of  application  open  to  casein  is  practically 
illimitable.''1 

Other  Uses  for  Casein.  —  Photographic  plates  may  be 
made  of  casein  and  have  some  advantages  over  glass  and 
celluloid,  being  lighter  in  weight  and  less  fragile  than  glass, 
non-inflammable,  and  less  likely  to  curl  during  developing 
than  celluloid. 

Casein  even  forms  an  important  part  in  a  brand  of  shoe 
polish.  It  is  used  to  treat  pulp  board  roofing  and  makes 
a  fireproof  covering  that  is  not  softened  by  the  heat  of  the 
sun.  Wooden  casks  used  for  beer,  wine,  etc.,  may  be  coated 
inside  with  a  solution  of  casein  and  formaldehyde.  This 
makes  an  impervious  seal.  Artists  and  scene  painters 
require  that  their  canvas  be  primed  before  it  is  painted. 
For  this  purpose  casein  gives  better  results  than  chalk, 
driers,  etc.,  because  it  does  not  crack  with  age.  The  soap- 
making  industry  claims  its  share  of  casein  for  use  in  toilet 
soaps,  perhaps  because  the  casein  aids  in  holding  and  re- 
enforcing  the  perfumes. 

Buttermilk  Poultry  Food.  —  A  poultry  food,  concentrated 
and  high  in  protein,  is  made  as  follows: 

Buttermilk  is  heated  in  tanks  to  about  160°  F.,  and  al- 
lowed to  stand  until  the  curd  has  settled.  The  whey  is 
then  drawn  off,  and  the  sediment,  a  mass  of  curd  with  a 
thick,  creamy  consistency,  is  run  into  barrels  and  sold  as 
poultry  food.  This  product,  though  heated  to  a  high 
temperature,  is  not  sterile,  but,  because  of  its  thick  con- 
sistency, has  good  keeping  qualities.  Like  sweetened  con- 
densed milk,  it  contains  insufficient  moisture  for  bacterial 
growth. 

1  Robt.  Scherer  —  Casein,  Its  Preparation  and  Utilization. 


CHAPTER  XXVIII. 

FERMENTED  MILKS. 

DURING  the  past  few  years  there  has  been  a  great  in- 
crease in  the  consumption  of  buttermilk  and  other  fer- 
mented milks.  Buttermilk  tablets  and  numerous  other  milk 
preparations  have  appeared  on  the  market,  for  most  of 
which  a  certain  medicinal  as  well  as  food  value  is  claimed. 
These  are  sold  under  various,  names,  such  as  Zoulak, 
Vitallac,  Yoghurt,  Matzoon,  Bacillae,  Kefir,  Kumiss, 
Lacto-Bacilline,  etc. 

In  practically  all  these  fermented  milks,  lactic-acid  fermen- 
tation is  the  main  one.  This  may  or  may  not  be  accompa- 
nied by  a  fermentation  causing  alcohol  and  carbon  dioxide  to 
be  formed.  This  latter  is  brought  about  chiefly  by  yeast 
ferments  acting  on  the  milk  sugar  and  other  added  sugars. 

Food  Value.  —  Since  these  products  are  all  made  of 
milk,  either  whole  or  skimmed,  the  composition  of  which 
is  but  slightly  changed  by  the  fermentation  it  undergoes, 
it  is  evident  that  the  food  value  of  these  fermented  products 
is  practically  the  same  as  that  of  fresh  milk.  There  is 
possibly  an  increased  digestibility  of  the  casein,  due  to 
the  fact  that  it  has  been  precipitated  and  is  in  a  very 
finely  divided  condition.  Those  products  containing  alco- 
hol and  carbon  dioxide  are  said  to  have  a  stimulating  action 
upon  the  digestive  organs. 

Principles  Involved.  —  In  Metchnikoff's  book  "  The 
Prolongation  of  Life  "  there  is  a  chapter  on  "  Lactic 
acid  inhibiting  intestinal  putrefactions."  He  states  that 
the  use  of  fermented  milks  in  combating  autointoxi- 

232 


FERMENTED   MILKS  233 

cation  —  toxic  fermentations  in  the  intestines  —  is  based 
on  the  principle  that  the  presence  of  lactic  acid  bacteria, 
and  the  products  of  their  growth,  prevent  or  inhibit  the 
growth  of  the  toxin-producing  germs  in  the  intestinal 
tract.  It  is  probable  that  the  beneficial  results  secured 
by  the  use  of  fermented  milks  are  due  to  a  combination 
of  causes:  First,  the  subduing  influence  of  the  lactic-acid- 
producing  germs  on  undesirable  ferments;  second,  the 
inhibiting  effect  of  the  lactic  acid  on  toxin-producing 
germs;  third,  the  influence  of  substances  not  necessarily 
acid  in  nature,  secreted  or  produced  by  the  milk  ferments; 
and  fourth,  the  stimulating  effects  and  nutritive  value  of 
all  the  milk  components. 

Whatever  the  physiological  action  may  be,  it  is  certain 
that  there  are  certain  benefits  to  be  derived  from  the  use 
of  fermented  milks. 

Tablet  and  Capsule  Cultures.  —  Rogers1  reports  that 
some  brands  of  tablets  and  capsules,  sold  under  various 
trade  names,  purporting  to  contain  great  numbers  of  the 
Metchnikoff  bacillus  or  Bacillus  bulgaricus,  were  examined 
in  the  Dairy  Division  laboratory,  and  were  found  to  con- 
tain very  few  of  these  desirable  bacteria.  When  these 
tablets  were  introduced  into  sterile  rnilk,  the  resulting 
fermentation  was  not  of  the  desirable  type.  The  milk 
was  curdled,  but  the  curd  showed  evidence  of  the  pres- 
ence of  peptonizers  and  gas  producers.  One  tablet  which 
was  advertised  to  contain  "  5,0x30,000  active  Metchnikoff 
units  "  was  found  to  contain  about  a  million  bacteria, 
nearly  all  of  which  were  of  the  class  usually  considered  un- 
desirable inhabitants  of  the  digestive  tract.  The  findings 
of  this  and  other  laboratories  indicate  that  little  reliance 
can  be  placed  on  dried  cultures  of  B.  bulgaricus. 
1  U.  S.  Dept.  of  Agri.,  Bu.  An.  Ind.,  26th  An.  Kept. 


234  DAIRY  TECHNOLOGY 

However,  this  does  not  apply  to  dry  cultures  of  B.  acidi 
lactici,  because  these  are  in  daily  use  in  butter  and  cheese 
factories  throughout  the  country,  and  are  known  to  contain 
a  sufficient  number  of  virile  lactic  bacteria  to  insure  a 
desirable  fermentation.  So-called  buttermilk  tablets  are 
simply  dry  cultures  pressed  into  tablet  form. 

The  germ  Bacillus  bulgaricus  is  capable  of  producing 
about  two  per  cent  of  lactic  acid  in  the  milk,  while  the 
ordinary  lactic-acid-producing  bacteria  in  milk  produce 
only  a  maximum  of  about  one  per  cent  acid. 

Buttermilk.  —  Most  common  of  all  fermented  milks  is 
the  by-product  of  the  butter-making  industry.  Butter- 
milk is  the  milky  portion  of  the  cream  that  remains  after 
the  fat  has  been  churned  out  of  the  cream.  As  cream  is 
normally  churned  sour,  the  casein  of  the  buttermilk  is 
in  a  precipitated  and  very  finely  divided  condition.  The 
casein  remains  suspended  in  the  liquid  for  several  hours, 
but  gradually  settles  to  the  bottom,  leaving  a  transparent 
whey  on  top;  occasional  stirring  keeps  the  buttermilk 
in  its  homogeneous  milky  condition.  This  universally 
common  beverage  needs  no  further  description.  When 
it  comes  from  fresh  and  properly  ripened  cream  it  is  a 
most  refreshing  and  delicious  drink. 

Composition.  —  The  composition  of  buttermilk  does 
not  differ  essentially  from  that  of  skim  milk.  Its  fat 
content  is  the  one  variable  factor,  and  this  depends  upon 
the  completeness  with  which  the  fat  was  churned  out. 
The  following  is  a  fair  example  of  the  composition  of  aver- 
age buttermilk:  Percent 

Water 9°  •  39 

Fat o .  50 

Casein  and  albumen 3 . 60 

Milk  sugar 4.06 

Lactic  acid o .  80 

Ash 0.75 


FERMENTED   MILKS 


235 


Artificial  Buttermilk.  —  Natural  buttermilk  from  fresh 
cream  ripened  with  a  lactic  culture  is  perhaps  the  best 
quality  of  this  product  that  can  be  secured;  but  in  many 
places  this  cannot  be  obtained  at  any  price.  Much  of  the 
buttermilk  of  to-day  has  undesirable  flavors  in  it.  Because 


FIG.  46.  —  Progress  milk  fermenting  machine. 


of  this  fact,  preparations  are  now  found  on  the  market 
which  have  all  the  characteristics  of  good  buttermilk,  but 
are  not  by-products  of  butter  making.  These  preparations 
are  made  of  whole  milk,  of  partly  skimmed  milk,  or  of 
wholly  skimmed  milk.  A  method  of  making  a  so-called 
"  skim-milk  buttermilk  "  is  as  follows: 


236  DAIRY  TECHNOLOGY 

Milk  to  be  used  may  be,  i,  skim  milk  fresh  from  the  sep- 
arator; 2,  pasteurized  skim  milk;  or,  3,  skim  milk  to  which 
5  per  cent  of  whole  milk  has  been  added,  to  make  the  fat 
content  similar  to  th^at  of  natural  buttermilk.  A  large  quan- 
tity of  a  good  starter  or  pure  culture  of  lactic-acid  bacteria 
is  next  added,  and  the  temperature  brought  to  70°  F. 
Enough  culture  is  added  to  have  the  milk  curdled  at  a  time 
when  it  will  be  convenient  to  churn  it.  The  development  of 
too  much  acidity  or  the  ripening  at  too  high  a  temperature 
causes  the  skim  milk  to  "  whey  off  "  after  it  has  curdled. 

When  thoroughly  curdled  the  skim  milk  is  placed  in 
a  churn  and  churned  for  forty  minutes,  just  as  cream  is 
churned  in  making  butter.  The  churning  process  thor- 
oughly breaks  up  the  curd  particles  and  produces  a  smooth, 
thick  liquid,  which  cannot  be  distinguished  from  ordinary 
good  buttermilk. 

Immediately  after  the  buttermilk  leaves  the  churn,  it 
should  be  cooled  to  50°  F.,  or  less,  to  prevent  further  de- 
velopment of  acidity.  Ordinary  milk  and  cream  coolers 
with  enlarged  holes  in  the  distributing  receptacle  may  be 
used  satisfactorily  for  cooling  buttermilk. 

It  is  well  to  strain  the  buttermilk  through  one  thickness 
of  cheesecloth  to  remove  any  pieces  of  curd  that  may  not 
have  been  broken  up.  The  buttermilk  is  then  put  into 
bottles  or  cans  and  held  at  a  low  temperature  until  delivered. 

Bacillus  Bulgaricus  for  Buttermilk.  —  One  objectionable 
property  possessed  by  both  natural  and  artificial  butter- 
milk is  that  the  precipitated  casein  settles  out  in  a  few 
hours,  leaving  clear  whey  on  top.  The  casein  is  easily 
mixed  with  the  whey  again,  but  the  settling  of  the  casein 
may  be  prevented  by  using  the  Bacillus  bulgaricus  as  the 
active  ferment.  This  produces  a  viscous  curd,  that  will 
not  settle  out. 


FERMENTED   MILKS  237 

If,  in  making  artificial  buttermilk,  the  skim  milk  be  in- 
oculated with  cultures  of  both  the  common  lactic-acid 
producer  and  the  Bulgarian  type,  good  results  will  not  be 
obtained,  because  the  two  types  of  organisms  have  different 
optimum  temperatures  for  growth.  The  common  lactic- 
acid  producer  gives  best  results  at  about  70°  F.,  while  the 
Bulgarian  type  should  be  grown  at  about  100°  F. 

To  get  the  best  results,  then,  a  batch  of  pasteurized 
skim  milk  is  inoculated  with  a  lactic-acid  culture,  and  the 
milk  ripened  exactly  as  is  done  when  making  a  starter  in 
a  creamery.  An  equal  quantity  of  pasteurized  skim  milk 
is  inoculated  with  the  Bulgarian  type  of  starter  and  incu- 
bated at  about  blood  heat  from  twenty-four  to  thirty  hours. 
It  will  then  contain  about  two  per  cent  acid  (as  much  as 
3  per  cent  acid  will  develop  in  3  days).  These  two  batches 
of  sour  milk  are  then  mixed  by  pouring  them  both  into  a 
churn  and  churning  the  milk  until  the  curd  is  all  broken  up 
and  a  smooth  product  is  secured. 

Buttermilk  Tablets.  —  There  are  several  brands  of  butter- 
milk tablets  sold  under  various  trade  names.  These  are 
useful  in  making  imitation  buttermilk  on  a  small  scale  in 
the  home.  One  method  of  using  these  tablets  is  described 
by  the  manufacturers  as  follows: 

"  Take  a  quart  of  fresh,  rich  milk,  put  it  in  a  clean  jar 
or  other  vessel  of  glass  or  earthenware,  and  add  thereto 
one-third  of  a  quart  of  hot  water.  The  amount  of  water 
may  be  varied  according  to  the  richness  of  the  milk,  the 
taste  of  the  individual  who  is  to  be  served,  or  the  require- 
ments of  the  patient  if  it  is  to  be  used  in  the  sick-chamber. 
The  purpose  in  adding  hot  water  is  to  raise  the  temperature 
of  the  milk  to  body  heat.  A  pinch  of  salt  is  now  stirred 
into  the  mixture  together  with  one  "  Lactone  "  tablet 
which  has  been  previously  powdered,  the  whole  being  well 
mixed  until  the  tablet  is  cHssolved.  The  jar  is  then  covered 


238  DAIRY  TECHNOLOGY 

and  set  aside  where  it  will  be  subjected  to  an  even  tempera- 
ture, such  as  that  of  the  average  kitchen.  In  twenty-four 
to  forty-eight  hours,  depending  upon  the  temperature,  the 
buttermilk  will  be  ready  for  use.  One  can  easily  tell,  by 
the  appearance  and  flavor  of  the  milk,  when  the  process 
of  thickening  and  fermentation  has  proceeded  far  enough. 
The  buttermilk  should  then  be  set  away  in  the  ice-box 
or  cellar.  Before  using,  it  should  be  thoroughly  stirred 
with  a  spoon  or  egg-beater  until  perfectly  smooth." 

This  artificial  buttermilk  is  sometimes  modified  at  soda 
fountains  by  the  addition  of  vichy  or  seltzer,  by  beating  an 
egg  into  it,  or  by  adding  vanilla,  lemon  or  other  flavors. 

Kefir.  —  Fermented  milks  have  been  used  by  the  people 
of  southern  Russia,  Turkey  and  the  Balkan  countries,  for 
many  centuries.  There  are  no  records  and  but  few  tradi- 
tions of  the  origin  of  the  fermented  milks  they  use,  and  it  is 
probable  that  their  preparation  and  use  developed  gradually 
by  cumulative  experience. 

One  of  the  first  fermented  drinks  known  to  Europeans 
was  kefir.  This  was  first  made  in  the  Caucasus  Moun- 
tains from  milk  of  cows,  sheep  and  goats.  Different 
tribes  made  this  drink  under  different  names l  such  as 
"  Hippe,"  "  Kepi,"  "  Khapon,"  "  Kephir  "  and  "  Kapher," 
all  of  which  names  are  said  to  be  derived  from  a  root  sig- 
nifying a  pleasant  taste. 

The  fermented  milk  forms  a  large  part  of  the  food  of  the 
Caucasian  mountaineers.  The  milk  is  prepared  in  leather 
bottles  made  of  goat  skins.  These  bottles  are  hung  where 
the  atmosphere  is  supposed  to  have  the  temperature 
favorable  to  the  proper  fermentation  of  the  milk.  This 
may  be  in  or  out  of  doors,  in  the  sun  or  in  the  shade.  A 
favorite  place  for  hanging  the  bags  is  near  a  doorway  where 
they  may  be  shaken  by  each  passer-by. 

1  U.  S.  Dept.  of  Agr.,  Bu.  An.  Ind.,  An.  Kept.,  1909. 


FERMENTED    MILKS  239 

In  order  to  prevent  the  escape  of  gas  when  drawing  milk 
from  the  bag,  a  string  is  first  tied  around  the  neck  so 
that  the  quantity  wanted  is  between  the  stricture  and  the 
mouth  of  the  bottle. 

One  characteristic  of  kefir  that  especially  distinguishes 
it  from  other  fermented  drinks  is  the  so-called  kefir  grain, 
which  is  used  to  start  the  proper  fermentation.  These 
kefir  grains  are  small,  yellowish,  convoluted  masses,  con- 
sisting largely  of  bacterial  threads  and  yeast  cells,  held  to- 
gether by  more  or  less  dried  milk.  When  these  grains  are 
added  to  milk  they  induce  a  fermentation  of  the  lactose, 
forming  alcohol  and  carbon  dioxide. 

Freudenreich1  describes  four  organisms  that  he  isolated 
from  kefir  grains.  Of  these,  one  was  yeast  to  which  he 
gave  the  name  "  Saccharomyces  kefir";  this  organism 
was  found  to  grow  best  at  22°  C.  (72°  F.);  but  not  at  all 
at  35°  C.  (95°  F.).  This  yeast  ferments  maltose  and  cane 
sugar,  but  not  lactose.  It  produces  a  peculiar  flavor  in 
milk.  The  same  investigator  found  two  organisms  of  the 
lactic-acid  type,  but  they  formed  gas  in  lactose  media. 
Another  organism  described  is  a  long,  slender  bacillus  to 
which  Freudenreich  gave  the  name  "  Bacillus  caucasica." 
The  properties  of  this  organism  indicate  that  it  resembles 
very  closely  the  well-known  Bacillus  bulgaricus.  If  Freu- 
denreich's  description  is  accurate,  B.  caucasicus  differs  from 
B.  bulgaricus  in  forming  gas  from  lactose  and  in  being  feebly 
motile.  No  one  of  these  organisms  grown  alone  produced 
kefir,  but  when  the  four  together  were  grown  in  milk, 
typical  kefir  was  produced  on  the  first  or  second  transfer. 

Various  investigators  have  found  different  organisms 
in  the  kefir  grain.  It  seems  probable  that  kefir  may  be 
produced  by  any  combination  of  bacteria  and  yeasts  that 
1  U.  S.  Dept.  Agr.,  Bu.  An.  Ind.,  An.  Kept.,  1909. 


240 


DAIRY  TECHNOLOGY 


produces  a  lactic  acid  and  an  alcoholic  fermentation  in 
milk.  Certain  organisms  may  be  necessary  for  the  de- 
velopment of  the  typical  kefir  flavor. 

Hammarsten  shows  the  changes  brought  about  in  cows' 
milk,  by  this  fermentation,  in  the  following  table: 

CHEMICAL  ANALYSIS  OF  KEFIR. 


Two  days 
old. 

Four  days 
old. 

Six  days 
old. 

Casein  

2     OO 

2    586 

2     ^64 

Lactalbumen  
Peptones  
Lactose  

0.425 
0.071 
3  .  7OO 

0.405 
0.089 
2.2*8 

0.390 
O.  I2O 
I    67O 

Fat  

3  .6lO 

T,  .6^0 

3  628 

Ash  

O.64I 

o.  624 

0.630 

Lactic  acid  

0.661? 

0.832 

0.900 

Alcohol 

o  230 

o  810 

I    IOO 

As  indicated  in  the  table,  the  only  constituent  of  the 
milk  appreciably  affected  is  the  lactose.  By  its  fermen- 
tation, lactic  acid,  alcohol  and  carbon  dioxide  are  formed. 
The  physical  condition  of  the  casein  is  changed,  and  it 
may  be  more  easily  digestible  because  of  its  finely  divided 
condition. 

The  following  directions  are  given  for  making  kefir 
when  the  grains  are  obtainable.  Soak  the  grains  in  warm 
water  to  soften  them,  changing  the  water  several  times. 
The  grains  are  ready  for  use  when  they  become  gelatinous 
and  whitish  and  rise  to  the  surface.  The  grains  are  then 
added  to  bottles  of  .pasteurized  milk  held  at  a  tempera- 
ture of  57°  to  60°  F.,  and  stirred  or  shaken  occasionally. 
After  8  to  10  hours,  the  grains  are  strained  out  and  the 
milk  put  into  tightly  stoppered  bottles.  The  fermenta- 
tion is  continued  at  the  same  temperature]  and  the  bottles 
shaken  occasionally  to  prevent  the  formation  of  hard 


FERMENTED   MILKS 


241 


lumps  of  curd.  After  about  twenty-four  hours,  the  kefir 
is  ready  for  use.  The  relative  amounts  of  alcohol  and 
lactic  acid  are  dependent  upon  the  temperature  of  fer- 
mentation. A  high  temperature  favors  the  alcoholic 
fermentation  and  a  slightly  low  temperature  favors  lactic- 
acid  fermentation. 

The   grains    are   used   merely   to    start   the    fermenta 
tion.     After  their  removal,  the  process  continues  with 
out   their   aid.      The   grains   may  be  washed  free   from 
curd,  dried  and  laid  aside  until  wanted  again.     In  their 
dry  state,  they  are  said  to  retain  their  vitality  for  several 
years. 

Kumiss.  —  When  explorers  and  missionaries  first  visited 
the  plains  of  European  Russia  and  central  and  south- 
western Asia,  they  found  the  native  nomadic  tribes  living 
to  a  large  extent  on  a  fermented  milk  now  known  as  kumiss. 
This  food  was  prepared  from  mares'  milk.  It  is  said  that 
the  proper  fermentation  was  induced  by  the  addition  to 
the  fresh  milk  of  pieces  of  decaying  flesh  or  vegetable 
matter.  These  tribes  are  great  horsemen,  and  they  have 
developed  mares  that  give  an  unusually  large  quantity 
of  milk. 

Mare's  milk  is  lower  in  nutritive  value  than  cows'  milk, 
as  the  following  table  shows : 1 

AVERAGE   COMPOSITION   OF   COWS'   MILK  AND  MARES' 

MILK. 


Water. 

Fat. 

Sugar. 

Casein. 

Albumen. 

Ash. 

Cow  

Per  cent. 
87.10 

Per  cent. 
3.90 

Per  cent. 
4-75 

Per  cent. 
3.00 

Per  cent. 
0.40 

Per  cent. 
0.71; 

6f\r* 

Mare  

90.00 

1.09 

I  . 

89 

0.31 

1  Richmond  —  Dairy  Chemistry, 


242 


DAIRY  TECHNOLOGY 


The  composition  of  kumiss  varies  somewhat  with  the 
age,  the  rapidity  of  the  fermentation,  and  the  nature  and 
extent  of  contamination  with  extraneous  organisms. 

COMPOSITION   OF  KUMISS  MADE  FROM  MARES'   MILK.1 


One  day 
old. 

Eight  days 
old. 

Twenty-two 
days  oid. 

Water                      

Per  cent. 
01    43 

Per  cent. 

02    12 

Per  cent. 
02   O7 

Alcohol    

2.67 

2    03 

2   08 

Lactic  acid  

o.  77 

I    08 

I    27 

Sugar  

1.63 

O    SO 

o  23 

Casein  

o.  77 

o.8s 

0.83 

Albumen  '.  

O.  2"? 

o.  27 

o.  24 

Albumose  

0.98 

o.  76 

o.  77 

Fat 

i   16 

I    12 

i  30 

Ash 

03? 

O    3"? 

o  3? 

The  fermentative  changes  in  kumiss  are  very  similar 
to  those  in  kefir.  The  main  difference  between  these  two 
products  is  the  origin  of  the  milk. 

American  Kefir  or  Kumiss.  —  Several  dairy  companies 
that  cater  to  fancy  city  trade  make  a  fermented  milk  and 
market  it  under  the  name  kefir  or  kumiss.  This  product 
is,  strictly  speaking,  not  kumiss,  because  it  is  made  of 
cows'  milk  instead  of  mares'  milk.  Nor  is  it  kefir,  because 
this  latter  product  is  the  result  of  fermentation  induced  by 
kefir  grains.  However,  the  prefix  " American"  might  be 
used  to  distinguish  it  from  that  of  Asiatic  origin.  This 
American  product  is  hygienic,  being  prepared  from  sanitary 
milk  and  fermented  by  carefully  selected  organisms. 

The  best  results  are  secured  by  inducing  an  alcoholic 
fermentation  in  good  buttermilk.  The  use  of  buttermilk 
insures  a  finely  divided  casein  and  a  smooth,  homogeneous 
product. 

For  the  alcoholic  fermentation,  ordinary  bread  yeast 

1  Richmond  —  Dairy  Chemistry. 


FERMENTED   MILKS  243 

may  be  used;  but  this  yeast  cannot  ferment  lactose,  hence 
cane  sugar  must  be  added  to  the  milk.  The  yeast  may  be 
added  directly  to  the  buttermilk,  but  better  results  are  se- 
cured as  follows:  To  four  ounces  of  boiled  water,  add  about 
ten  grams  of  cane  sugar  and  one  third  of  a  yeast  cake.  Do 
not  add  the  yeast  till  water  is  cooled.  Keep  in  a  warm 
place  (70°  to  80°  F.)  over  night,  or  for  about  ten  hours. 
This  produces  an  active  culture  of  the  yeast.  To  each 
quart  bottle  of  buttermilk  add  15  grams  of  cane  sugar 
and  2  c.c.  of  yeast  culture.  Cap  the  bottles  with  patent 
stoppers  or  other  tight  caps  that  will  withstand  gas  devel- 
opment within  the  bottle.  Keep  at  a  temperature  of  about 
60°  F.  for  from  three  to  four  days  with  occasional  shaking 
to  break  up  the  curd.  At  the  end  of  this  time,  the  prod- 
uct will  be  ready  for  use.  Fermentation  at  a  high  tem- 
perature, and  continued  for  too  long  a  time,  produces  a 
strong  undesirable  flavor.  The  amount  of  alcohol  and 
carbon  dioxide  developed  depends  upon  the  amount  of 
sugar  added  to  the  buttermilk.  The  theoretical  quantity 
of  alcohol  formed  is  about  one  half  the  quantity  of  sugar 
fermented.  The  carbon  dioxide,  rather  than  the  alcohol, 
is  the  desirable  product  of  the  yeast  fermentation.  The 
quantity  of  sugar  to  be  added  is  governed  by  the  quantity 
of  carbon  dioxide  desired.  Fifteen  grams  of  sugar  in  one 
quart  of  buttermilk  (i  per  cent  of  sugar)  produces  the 
desirable  effervescence,  and  the  sharp  taste  of  charged 
water,  but  will  not  cause  an  excess  of  gas. 

A  similar  product  may  be  made  from  skim  milk  instead 
of  buttermilk.  In  this  case  the  milk  should  be  pasteurized 
and  a  slightly  larger  percentage  of  sugar  (two  to  three  per 
cent)  be  used.  This  product  lacks  the  sharp  acid  flavor 
of  the  buttermilk  product,  but  has  the  pleasant  gas- 
charged  flavor. 


244  DAIRY  TECHNOLOGY 

Yoghurt.  —  The  people  inhabiting  the  countries  border- 
ing the  eastern  end  of  the  Mediterranean  prepare  a  milk 
that  is  quite  different  from  those  previously  mentioned. 
Yoghurt  is  a  thick  curdled  milk,  high  in  acid,  but  contain- 
ing little  or  no  alcohol.  It  is  prepared  from  goats',  buf- 
falos',  and  cows'  milk.  This  is  usually  boiled,  and  some- 
times the  boiling  is  continued  until  the  milk  is  evaporated 
to  one  half  its  original  volume.  In  the  latter  case  the 
product  has  the  consistency  of  pudding  and  instead  of 
being  used  as  a  drink,  is  eaten,  sometimes  with  the  addi- 
tion of  dates,  bread  or  other  food. 

The  different  people  of  this  region  have  various  names  1 
for  their  prepared  milks,  but  the  products  are  all  very 
similar.  The  Turks  use  the  names  "yoghurt,"  "  yahourth  " 
and  "jugurt";  the  Balkan  people,  "  kisselo  melko  " ;  the 
Armenians,  "mazum";  the  Sardinians,  "gioddu";  and 
the  Egyptians,  "  leben  "  or  "  leben  raib." 

Several  investigators  have  studied  these  fermented  milks 
from  a  bacterial  standpoint,  and  have  isolated  certain 
organisms  and  applied  various  names  to  them.  But  the 
opinion  generally  held  by  investigators,  at  the  present 
time,  is  that  the  various  organisms  necessary  for  the  pro- 
duction of  milks  of  the  yoghurt  class,  all  may  be  included 
under  the  name  Bacillus  bulgaricus. 

This  Bacillus  bulgaricus  has  a  very  characteristic  action 
when  grown  in  milk.  In  a  few  hours  at  the  optimum 
temperature  (about  100°  F.)  a  curd  is  formed  that  is  rather 
soft,  sometimes  shiny,  and  does  not  settle  to  the  bottom  or 
"  whey  off  "  upon  long  standing.  The  acidity  of  the  milk 
may  reach  two  per  cent  in  twenty  hours  and  three  per  cent 
after  several  days. 

1  U.  S.  Dept.  of  Agr.,  Bu.  An.  Ind.,  An.  Kept.,  1909. 


FERMENTED  MILKS  245 

Ropy  Milk.  —  Fermentation  of  milk  by  Streptococcus 
hollandicus  produces  a  slightly  sour  milk  with  a  thick 
slimy  consistency. 

In  Norway  and  Sweden,  and  also  in  Finland,  it  is  a 
commercial  article,  and  is  brought  into  the  towns  by  the 
peasants  to  be  sold  in  much  the  same  way  as  butter  is 
brought  into  the  towns  to  be  sold  here,  only  on  not  so  large 
a  scale.  In  Holland  it  is  called  "  langewej,"  and  is  there 
used  chiefly  as  a  starter  to  control  the  gassy  fermentation 
in  the  manufacture  of  Edam  cheese. 

Moscow  Sour  Cream. — This  product  is  made  from  cream 
that  has  undergone  a  good  acid  fermentation.  Having  been 
thoroughly  mixed  in  the  starter,  the  mass  is  allowed  to  stand 
undisturbed  at  a  temperature  between  77°  and  90°  F.,  for 
six  or  more  hours  until  ripe.  When  it  reaches  such  a 
point  that  an  acid  flavor  can  just  be  detected,  it  is  taken 
to  a  cold  room  or  ice  box.  While  it  is  being  cooled  all 
the  cream  thickens  to  a  uniform  mass  without  clots,  and 
has  a  pleasant,  acid  taste.  This  sour  cream  is  thick 
and  solid.  It  may  be  cut  with  a  knife  like  butter.  The 
fermentation  is  effected  in  wooden  or  glass  vessels,  never 
in  metal  vessels.  The  latter  would  give  it  a  metallic  taste. 
There  is  no  need  whatever  to  press  the  sour  cream,  for  the 
whole  of  the  cream  is  used  without  any  separation  of  whey. 
The  sour  cream  must  not  be  agitated.  When  putting  it 
into  boxes  or  casks,  care  must  be  taken  to  put  it  in  layer  on 
layer.  It  can  be  quite  safely  transported  in  wooden  boxes 
lined  with  parchment.  As  the  sour  cream  is  solid,  there  is 
no  necessity  to  add  any  preservative.  With  a  temperature 
in  the  cellar  of  48°  to  55°  F.  when  the  casks  or  cases  are 
put  in,  the  sour  cream  will  keep  for  three  or  four  months. 

There  are  some  milk  preparations  which  are  allied  to 
fermented  milks,  but  which  have  undergone  no  special 


246  DAIRY  TECHNOLOGY 

fermentation.     Carbonated  milk   and  Devonshire  cream 
come  in  this  class. 

Clotted  or  Devonshire  Cream.  —  Devonshire  cream  used 
to  be  a  special  product  of  the  West  of  England.  How- 
ever, it  can  be  made  anywhere,  provided  the  milk  be  rich 
and  the  treatment  correct.  The  milk  should  be  strained 
while  warm  into  the  pans  in  which  it  is  to  be  scalded. 
These  pans  are  from  6  to  8  inches  deep  and  about  eighteen 
inches  in  diameter,  and  are  made  to  fit  into  a  pan  of  water, 
which  in  turn  fits  on  to  a  stove. 

The  milk  sets  for  twelve  hours  until  the  cream  has  risen. 
Then  the  fire  is  lighted  and  the  cream  is  scalded.  The 
water  jacket  prevents  the  temperature  rising  too  high, 
which  would  give  a  cooked  taste  to  the  product;  and  when 
the  process  is  complete,  handles  on  the  side  of  the  pan 
enable  it  to  be  lifted  off  easily.  The  great  art  in  scalding 
is  to  get  a  thick  unbroken  layer  of  cream  on  the  surface 
with  a  wrinkled,  yellow  appearance.  The  heating  should 
be  done  slowly,  until  a  temperature  of  from  180°  to 
185°  F.  is  attained,  at  the  rate  of  about  2°  per  minute  'for 
an  hour.  » 

The  cooling  is  accomplished  either  by  raking  out  the 
fire  for  slow  cooling,  or  by  setting  the  pan  in  cold  water 
for  quick  cooling,  after  which  the  cream  is  ready  for  use 
or  for  putting  into  jars.  For  quick  work,  on  a  large  scale, 
the  cream  is  sometimes  separated,  and  then  a  thick  layer 
put  back  onto  pans  of  separated  milk,  and  then  scalded. 
The  cream  must  be  scalded  on  the  milk,  as  it  cannot  be 
done  satisfactorily  alone.  Both  the  milk  and  the  cream 
keep  well,  because  the  process  is  equivalent  to  pasteuri- 
zation. For  small  quantities,  any  kind  of  a  pan  on  any 
kind  of  a  stove  will  do  if  conditions  are  observed  and  the 
process  carried  out  carefully. 


FERMENTED   MILKS  247 

Carbonated  Milk.  —  Van  Slyke  and  Bosworth,1  in 
making  a  study  of  the  chemical  changes  in  kumiss  made 
from  cows'  milk,  noticed  that  lactic  acid  formed  in  it  much 
more  slowly  than  in  ordinary  milk.  This  was  found  to 
be  due  to  the  action  of  carbon-dioxide  gas  under  pressure. 

A  series  of  experiments  was  conducted  in  order  to  ascer- 
tain the  effect  of  carbon  dioxide  under  pressure  upon  the 
development  of  lactic  acid  in  milk.  The  results  of  these 
experiments  are  reported  in  the  New  York  Geneva  Sta- 
tion Bulletin  292. 

The  milk  used  was  (i)  fresh,  separator  skim  milk;  (2) 
fresh  whole  milk,  drawn  and  handled  under  good  hygienic 
conditions;  (3)  fresh  skim  milk  pasteurized  at  185°  F., 
and  (4)  fresh  whole  milk  pasteurized  at  185°  F. 

The  pressures  of  gas  employed  were  71,  150  and  175 
pounds  per  square  inch. 

The  most  effective  method  of  treating  the  milk  was  to 
charge  it  with  carbon-dioxide  gas  at  the  desired  pressure 
in  a  tank  such  as  is  used  in  bottling  establishments  in 
preparing  carbonated  drinks,  and  then  to  fill  into  bottles. 

The  carbonated  milk  was  kept  at  temperatures  varying 
from  35°  to  70°  F. 

Pasteurized  milk,  carbonated,  kept  for  five  months 
with  little  increase  of  acidity.  Fresh,  raw  whole  milk, 
carbonated,  kept  in  one  experiment  for  about  the  same 
length  of  time. 

Carbonated  milk  makes  a  pleasant  beverage  and  may 
find  practical  use  as  a  healthful  drink.  It  may  also  be 
found  useful  for  invalids  and  children. 

The  effect  of  carbonating  milk  upon  organisms  other 
than  lactic  has  not  yet  been  studied. 

Milk  carbonated  under  a  pressure  of  70  pounds  comes 
1  Geneva,  N.  Y.,  Bui. 


248  DAIRY  TECHNOLOGY 

from  the  bottle  as  a  foamy  mass,  more  or  less  like  kumiss 
that  is  two  or  three  days  old.  It  has  a  slightly  acid, 
pleasant  flavor,  due  to  the  carbon  dioxide,  and  tastes  some- 
what more  saline  than  ordinary  milk.  In  the  case  of  car- 
bonated milk  pasteurized  at  185°  F.,  there  is  something 
of  a  "  cooked  "  taste.  Though  the  cream  separates  in 
the  bottle,  it  is  thoroughly  remixed  by  a  little  shaking  as 
the  milk  comes  from  the  bottle,  and  there  is  no  appearance 
of  separate  particles  of  cream.  All  who  have  had  occa- 
sion to  test  the  quality  of  carbonated  milk  as  a  beverage 
agree  that  it  is  a  pleasant  drink.  Milk  bottled  under  a 
pressure  of  150  pounds  of  carbon  dioxide  is  about  the  con- 
sistency of  whipped  cream.  On  standing  a  short  time, 
it  changes  into  a  readily  drinkable  condition.  From  the 
authors'  experience  it  would  seem  that  carbonated  milk 
might  be  made  a  popular  beverage. 


CHAPTER  XXIX. 

CONDENSED  AND  EVAPORATED  MILK. 

THE  purpose  of  condensing  milk  is  twofold:  to  improve 
its  keeping  property,  and  to  lessen  its  bulk.  These  two 
objects  must  be  attained  without  changing  any  of  the 
essential  properties  of  any  of  the  milk  components  and 
still  have  these  components  soluble  again  when  water  is 
added.  In  this  latter  form,  it  should  have  all  the  flavor 
and  appearance  of  fresh  normal  milk. 

Extent  of  the  Industry.  —  The  United  States  Census 
Report  of  1905  reports  81  milk-condensing  factories  in 
the  United  States  during  that  year.  These  factories 
were  distributed  over  17  states  and  manufactured  about 
320,000,000  pounds  of  condensed  milk.  During  the  past 
six  years  this  industry  has  been  making  very  rapid  strides. 
The  number  of  condenseries  has  about  doubled,  and  the 
pounds  of  finished  product  have  reached  the  half-billion 
mark. 

The  consumption  of  condensed  milk  is  increasing  rapidly, 
not  only  in  the  tropic  and  arctic  regions,  on  shipboard,  in 
mining  and  lumber  camps  where  little  or  no  milk  is  pro- 
duced, but  also  in  our  local  home  markets.  The  ice-cream 
industry  is  responsible  for  a  considerable  demand  on  the 
condensed  milk  supply.  The  baker  and  candy  maker  also 
use  their  share,  and  many  housewives,  especially  in  our 
large  cities,  find  the  canned  product  more  reliable  than  that 
furnished  daily  by  the  city  milk  plant.  This  is  true  mainly 
in  cities  that  have  had  no  pure  milk  crusade. 

249 


250  DAIRY  TECHNOLOGY 

United  States  Standards.  —  In  the  Federal  Food  and 
Drug  Act  that  went  into  effect  January  i,  1907,  condensed 
and  evaporated  milk  are  classified  as  follows: 

"  Condensed  Milk,  Evaporated  Milk,  is  milk  from  which 
a  considerable  portion  of  water  has  been  evaporated  and 
contains  not  less  than  twenty-eight  (28)  per  cent  of  milk 
solids  of  which  not  less  than  twenty-seven  and  five-tenths 
(27.5)  per  cent  is  milk  fat. 

"Sweetened  Condensed  Milk  is  milk  from  which  a  con- 
siderable portion  of  water  has  been  evaporated  and  to 
which  sugar  (sucrose)  has  been  added,  and  contains  not  less 
than  twenty-eight  (28)  per  cent  of  milk  solids,  of  which  not 
less  than  twenty-seven  and  five- tenths  (27.5)  per  cent  is 
milk  fat. 

"  Condensed  Skim  Milk  is  skim  milk  from  which  a  con- 
siderable portion  of  water  has  been  evaporated." 

Evaporated  milk  is  unsweetened  condensed  milk  put 
up  in  hermetically  sealed  cans  holding  from  six  and  one- 
half  to  twenty  ounces,  and  also  in  quart  and  gallon  cans. 
This  product  is  somewhat  deceiving  to  the  eye.  It  appears 
to  be  very  thick  and  rich,  while,  as  a  matter  of  fact,  the  milk 
is  condensed  only  from  about  two  or  two  and  one-half  parts 
of  the  fresh  milk,  to  one  of  evaporated  milk.  It  contains 
no  cane  sugar  to  act  as  a  preservative,  but  is  sterilized  by 
steam  under  pressure. 

Plain  condensed  milk  is  made  in  a  similar  manner,  but 
is  not  sterilized.  It  is  usually  marketed  in  ordinary  milk 
cans  in  the  same  general  manner  as  fresh  milk.  It  will 
keep  in  good  condition  for  from  ten  to  thirty  days,  if  kept  at 
a  low  temperature.  It  is  intended  for  early  consumption, 
and  is  used  by  hotels,  restaurants,  and  candy  and  ice-cream 
makers,  as  starter  milk  in  butter  factories,  and  to  some 
extent  in  private  houses. 

Sweetened  condensed  milk  is  that  to  which  sufficient 


CONDENSED  AND   EVAPORATED   MILK  251 

sugar  has  been  added  to  prevent  fermentation.  This  is  a 
very  thick  syrupy  product  containing  about  forty  per  cent 
cane  sugar  and  twenty-eight  to  thirty-six  per  cent  milk 
solids. 

Quality  of  Raw  Product.  —  The  quality  requirements 
of  milk  for  condensing  purposes,  especially  for  evaporated 
milk,  are  higher  than  for  any  other  purpose.  The  conden- 
sary  usually  keeps  an  inspector  on  the  road  all  the  time, 
and  the  patrons  are  required  to  follow  his  suggestions. 
Some  condenseries  require  all  patrons  to  use  a  certain  style 
of  milk  cooler,  and  require  the  milk  to  be  below  a  certain 
temperature  —  55°  to  60°  F. — when  delivered  at  the  fac- 
tory. Bad  odors  or  dirt  in  the  milk  is  not  tolerated. 

The  condensery  operator  claims  that  milk  from  cows  fed 
on  silage,  brewers'  grain  and  similar  feeds,  curdles  much 
more  readily  than  that  from  cows  not  fed  on  these  feeds; 
hence  where  evaporated  milk  is  made,  such  feeds  are  usually 
forbidden.  In  some  instances  these  feeds  are  permitted, 
but  the  time  of  feeding  and  the  amount  fed  are  restricted. 

The  following  rules  and  regulations  are  enforced  by  the 
Pacific  Coast  Condensed  Milk  Company: 

"  i.  All  cows  must  be  healthy  and  in  good  flesh  at  all 
times,  be  milked  at  regular  hours,  morning  and  evening, 
and  in  a  cleanly  manner.  They  must  be  kindly  treated 
and  no  milk  will  be  accepted  from  cows  that  are  overheated 
or  excited  from  any  cause. 

2.  The  milk  must  be  cooled  and  aerated  immediately 
after  milking,  and  put  into  tin  cans  which  have  been  rinsed 
in  clean,  cold  water.     Both  milk  and  cans  must  be  kept1 
where  they  will  be  free  from  filth  or  bad  odors. 

3.  The  cans  of  milk  must  be  left  with  the  lids  off,  in 
cold  water  to  prevent  rise  in  temperature,  until  ready  for 
delivery.     They  should  be  covered  with  wire  screen  or  clean 
cloth  to  prevent  foreign  substances  from  getting  into  the 
milk. 


252  DAIRY  TECHNOLOGY 

4.  By  the  use  of  coolers  milk  can  be  reduced  immediately 
to  within  a  few  degrees  of  the  temperature  of  the  water 
used.     Milk  higher  than  65°  F.  will  not  be  accepted  at 
the  factory. 

5.  Tin  pails  only  are  to  be  used  to  milk  in,  and  they  must 
be  thoroughly  washed  and  scalded  every  time  they  are 
used,  and  allowed  to  dry  in  the  open  air,  in  the  sun  if  pos- 
sible, and  must  not  be  used  for  any  other  purpose. 

6.  The  night's  and  morning's  milk  shall  not  be  mixed, 
and  no  milk  shall  be  kept  over  to  be  delivered  at  a  sub- 
sequent time. 

7.  The  evening's  milk  must  be  kept  at  or  below  a  tem- 
perature of  55°  F.,  and  out  of  contact  with  dirt  or  bad  odors. 

8.  When  the  cans  in  which  the  milk  is  transported  to 
the  factory  are  not  in  use,  they  shall  be  turned  down  on  a 
rack  with  the  covers  off,  except  only  when  in  transit. 

9.  All  milk,  including  the  strippings,  shall  be  delivered. 
No  milk  shall  be  delivered  which  is  taken  from  cows  that 
have  calved  within  twelve  days,  nor  from  any  cow  that  is 
to  calve  within  thirty  days. 

10.  If  there  is  good  reason  to  suspect  that  water  has 
been  added,  or  cream  removed,  or  that  milk  has  not  been 
properly  cooled,  or  that  it  has  been  injured  by  carelessness 
or  from  filth,  or  if  the  cans  are  filthy,  such  milk  will  be 
refused. 

1 1 .  Cows  must  not  be  allowed  to  eat  sour,  noxious  grasses 
and  weeds,  or  other  objectionable  food.     No  still  or  brewers' 
grains,    or   slops,    sorghum   or   glucose   refuse,    cabbages, 
ensilage  or  other  damaged  or  decayed  food  of  any  kind 
shall  be  fed  under  any  circumstances,  and  sugar  beets,  tur- 
nips and  red  carrots  only  in  small  quantities  and  soon  after 
milking. 

12.  Stables  and  sheds  where  cows  are  kept  must  be  clean 
and  free  from  foul  odors. 

13.  Our  inspector  shall  have  the  right  to  visit  the  prem- 
ises of  our  patrons  at  any  time,  and  all  suggestions  made 
by  him  must  be  carefully  carried  out. 

14.  We  shall  refuse  milk  from  anyone  violating  these 
rules." 


CONDENSED  AND   EVAPORATED  MILK  253 

The  Condensing  Process.  —  The  condensing  of  milk 
has  been  developed  to  its  present  state  of  perfection  only 
by  the  expenditure  of  much  time  and  money  in  experi- 
menting. To  be  a  high-grade  marketable  product,  the 
milk  must  be  condensed  under  very  exact  conditions, 
and  brought  to  the  proper  degree  of  condensation.  Milk 


FIG.  47.  —  Milk  condensing  pan. 

not  properly  condensed  may  have  a  marked  cooked  flavor, 
or  be  curdy,  or  contain  lumps  of  butter,  instead  of  being 
smooth  and  homogeneous. 

To  avoid  the  cooked  flavor  and  to  prevent  the  milk 
from  burning  to  the  inside  of  the  condenser  it  is  necessary 
to  condense  or  evaporate  at  a  low  temperature. 

The  boiling-point  of  milk,  like  that  of  other  liquids, 
varies  according  to  atmospheric  pressure.  The  boiling- 


254  DAIRY  TECHNOLOGY 

point  of  milk  is  a  little  higher  than  that  of  water,  viz., 
about  2i4°F.  At  such  a  temperature,  during  so  long  a 
time  as  is  necessary  for  evaporation,  the  milk  assumes  a 
marked  cooked  flavor,  and  some  natural  characteristics 
of  the  milk  components  change.  For  instance,  the  sugar 
caramelizes,  the  fat  melts  into  oil  so  as  to  make  remixing 
difficult,  some  albumen  coagulates,  and  a  portion  of  the 
calcium  phosphate  salts  separates  from  the  casein.  If  the 
atmospheric  pressure  is  reduced  so  as  to  bring  the  boiling- 
point  to  from  120°  to  130°  F.,  evaporation  takes  place  and 
the  undesirable  changes  incident  to  higher  heat  are  absent. 
This  is  effected  in  the  apparatus  known  as  a  vacuum  pan. 
Such  a  pan  consists  usually  of  four  chief  parts : 

1.  The  pan  or  kettle,  which  holds  the  milk  and  which 
is  usually  lined  with  bright  copper. 

2.  A  steam  jacket,  around  the  pan  or  steam  coils,  or 
both,  to  supply  the  heat  necessary  for  evaporation. 

3.  The  condenser,  connecting  with  the  top  part  of  the 
pan   for   condensing   the   steam   and   creating   additional 
vacuum.     Cold  water  constantly  circulates  through  the 
condenser. 

4.  The  vacuum  pump,  used  for  reducing  the  atmospheric 
pressure  in  the  pan  by  pumping  out  the  air  and  for  remov- 
ing steam  and  water  in  case  a  wet  vacuum  is  used.     If 
a  dry  vacuum  is  used,  the  pump  removes  only  the  air, 
and  the  water  flows  out  by  its  own  gravity. 

So  far  as  known,  Mr.  Gail  Borden  of  the  United  States 
was  the  inventor  of  the  vacuum  method  of  milk  conden- 
sation. A  patent  was  taken  out  by  him  in  the  United 
States  in  1856.  One  objection  to  this  first  condensed 
milk  was  that  it  would  keep  only  a  few  weeks. 

Mr.  C.  A.  Page,  then  United  States  consul  at  Zurich, 
improved  the  Borden  method  by  adding  sugar.  This 


CONDENSED  AND   EVAPORATED   MILK  255 

made  the  concentration  of  nutrients  so  great  that  bacteria 
did  not  develop  in  it,  even  if  constantly  exposed  to  the  air. 
Mr.  Page  started  a  factory  in  Switzerland.  In  1866  he 
was  succeeded  by  the  Anglo-Swiss  Milk  Company,  which 
located  a  large  factory  on  Lake  Zug  in  the  canton  of  that 
name.  This  company  prospered  and  so  far  as  known  still 
exists  and  has  branches  in  the  United  States,  Germany, 
England  and  Switzerland.  It  supplied  practically  the  whole 
of  Europe  with  condensed  milk.  The  Borden  Condensed 
Milk  Company  is  one  of  the  largest  in  this  country. 

Before  the  milk  is  put  into  the  vacuum  pan,  it  is  heated 
and  run  through  a  clariner  to  remove  all  physical  dirt 
and  some  of  the  objectionable  odors.  Then  it  is  passed 
on  to  the  vacuum  pan,  where  the  condensation  takes 
place. 

Enough  air  is  pumped  out  of  the  vacuum  pan  so  that 
it  will  show  a  vacuum  or  air  pressure  of  24  to  28  inches 
as  measured  by  a  mercurial  column  vacuum  gauge.  In 
such  a  vacuum,  milk  boils  at  a  temperature  of  from  105° 
to  135°  F.  It  is  very  essential  to  keep  the  vacuum  pump 
working  uniformly  in  order  to  maintain  a  constant  vacuum. 
Should  the  vacuum  be  greatly  lessened,  evaporation  would 
cease,  the  temperature  of  the  milk  would  rise,  and  the 
entire  batch  of  milk  might  be  spoiled.  Condensation  is 
continued  until  a  sample  drawn  from  the  pan  shows  the 
proper  degree  of  concentration  as  determined  by  a  Baume 
hydrometer. 

Degree  of  Concentration.  —  This  is  undoubtedly  the 
most  important  point  in  the  process.  When  concentrated 
too  much,  the  result  may  be  curdled  milk.  When  not 
sufficiently  concentrated,  the  fat  separates  and  may  churn 
in  subsequent  processes.  In  either  case  the  commercial 
value  of  the  product  is  greatly  lessened. 


256 


DAIRY  TECHNOLOGY 


By  concentrating  the  milk  by  evaporation  of  water  the 
per  cent  of  acid  and  other  non-volatile  chemicals  are  in- 
creased. This  may  be  illustrated  as  follows:  Supposing 
the  milk  to  be  condensed  contained  0.2  per  cent  acid,  and 
this  milk  was  condensed  to  one  half  its  volume,  the  per 
cent  acid  contained  in  the  finished  product  would  be  twice 
its  original  per  cent,  or  0.4  per  cent.  By  further  conden- 
sation, the  per  cent  acid  will  increase  proportionately. 
The  great  importance  of  having  milk  with  a  low  acid  con- 
tent for  condensed  milk  is  readily  understood.  This  in- 
creased per  cent  of  acidity  after  condensation  and  increased 
heat  during  the  condensation  period  are  likely  to  cause 
the  milk  to  curdle  and  become  lumpy.  This  latter  is 
very  undesirable.  Condensed  milk  should  have  a  uni- 
formly smooth  body.  If  it  has  not,  the  trade  rejects  it. 
It  is  possible  that  other  components  of  milk  affect  the 
properties  of  the  finished  product  similarly  to  the  acid  on 
concentration  and  heating. 

The  following  table1  shows  the  results  of  evaporating 
fresh  milk  to  different  degrees  of  concentration. 


Lot  No. 

Concentration. 

Per  cent  of  acid. 

Condition  of  casein. 

I 

1.58: 

0.30 

Not  precipitated. 

2 

1.74  : 

0-34 

Not  precipitated. 

3 

1.9    : 

0.40 

Not  precipitated. 

4 
5 

1.99  : 
2.  ii  : 

0-43 
0.48 

Not  precipitated. 
Small  lumps  of  curd. 

6 

2.25  : 

0-54 

Large  lumps  of  curd. 

The  different  lots  of  evaporated  milk  were  made  from 
the  same  batch  of  fresh  milk. 

Another  kind  of  undesirable  condensed  milk  is  that 
which  is  churned.  It  is  important  that  the  butter  fat  be 
properly  emulsified  with  the  remainder  of  the  milk  com- 

1  Indiana  Bui.  143. 


CONDENSED  AND   EVAPORATED   MILK 


257 


ponents.  Butter  lumps  in  the  condensed  milk  are  due 
chiefly  to  the  condensed  milk  being  too  thin  when  put  into 
the  shaker.  This  condition  of  the  fat  may  also  partially 
be  caused  by  allowing  the  condensed  milk  to  cool  without 
shaking  immediately  after  it  has  been  taken  out  of  the  steri- 
lizing oven.  Except  in  case  of  accidents  to  machinery,  this 
factor  seldom  enters  in  as  a  cause  of  churned  condensed  milk. 

A  third  factor  causing  losses  to  the  condense  ries  is  im- 
proper sterilization.  Even  though  the  milk  is  sterilized 
in  steam-pressure  ovens,  some  ferments  are  not  destroyed. 
In  order  to  be  sure  that  the  sterilization  has  been  complete, 
the  sealed  cans  containing  the  condensed  milk  are  put  into 
a  testing  room.  The  temperature  of  this  room  is  kept  uni- 
form and  high  enough  for  rapid  growth  of  germs.  If  any 
ferments  remain,  the  cans  show  it  in  a  few  days  by  bulging 
or  distended  sides.  This  latter  is  due  to  the  development 
of  gas.  The  cans  showing  this  characteristic  are  discarded. 

Hunziker  1  carried  on  some  experiments  in  connection 
with  the  Indiana  Condensed  Milk  Company  at  Sheridan, 
Indiana,  to  demonstrate  the  effect  of  different  degrees  of 
concentration  on  the  marketable  properties  of  evaporated 
milk.  The  results  are  tabulated  below: 

JUNE  EXPERIMENT. 


No. 

Concentration. 

Milk  solids, 
per  cent. 

Condition  of  sample  one  month  after 
manufacture. 

I 
2 

3 

4 

5 

1.61  :  i 

1.96  :  i 
2  .  oo  :  i 
2  .  20  :  i 

2.52  :  i 

20.40 

24.87 
25.38 
28.02 

31-99 

Fat  separated  and  churned,  no 
curd. 
Smooth,  no  separation,  no  curd. 
Smooth,  no  separation,  no  curd. 
Curdy,  lumps  of  curd,  fat  not 
separated. 
Curdy,  lumps  of  curd,  fat  not 
separated. 

Total  solids  in  fresh  milk,  12 .68  per  cent. 

Acidity  in  fresh  milk  o.  16  per  cent 

1  Indiana  Bui.  143. 


258 


DAIRY  TECHNOLOGY 

AUGUST  EXPERIMENT. 


No. 

Concentration. 

Milk  solids, 
per  cent. 

Condition  of  sample  one  month  after 
manufacture. 

I 

1.94  :  i 

22.79 

Fat  separated  and  churned,  no 

curd. 

2 

2.  ii  :  i 

24.81 

Fat  separated  and  churned,  no 

curd. 

3 

2.  21  :  i 

26.01 

Smooth,  no  separation,  no  curd. 

4 

2.33  :  i 

27-33 

Curdy,  small  lumps  of  curd,  no 

separation. 

5 

2.5    :  i 

29-37 

Curdy,  lumps  of  curd,  no  sepa- 

ration. 

Total  solids  in  fresh  milk,  n  .  75  per  cent. 
Acidity  in  fresh  milk,  0.12  per  cent. 

NOVEMBER  EXPERIMENT. 


No. 

Concentration. 

Milk  solids, 
per  cent. 

Condition  of  sample  one  month  after 
manufacture. 

I 

1.58      I 

21.12 

Fat  separated  and  churned,  no 

curd. 

2 

1.74      I 

23-25 

Fat  separated  and  churned,  no 

curd. 

3 

1.9        I 

25.48 

Smooth,  no  separation,  no  curd. 

4 

1.99      I 

26.62 

Smooth,  no  separation,  no  curd. 

5 

2.  II       I 

28.23 

Curdy,  small  lumps  of  curd,  no 

separation. 

6 

2.25       I 

30.10 

Curdy,  lumps  of  curd,  no  sepa- 

ration. 

Total  solids  in  fresh  milk,  13.40  per  cent. 
Acidity  in  fresh  milk,  0.17  per  cent. 

The  following  conclusions  are  drawn  by  the  investigator: 

"  These  experiments  show  that,  in  this  particular  factory, 
a  hard  curd  is  formed  in  the  evaporated  milk  when  the  con- 
centration is  carried  as  far  as  28  per  cent  solids.  They 
further  show  that  there  is  a  distinct  difference  in  the  be- 
havior of  the  milk  at  different  times  of  the  year.  In  spring 
or  early  summer  there  is  a  greater  tendency  for  curdy  milk 
than  later  in  the  season.  It  has  been  experimentally 


CONDENSED  AND   EVAPORATED   MILK  259 

shown  that,  in  some  localities  and  at  certain  seasons  of 
the  year,  a  marketable  evaporated  milk  cannot  be  made 
when  the  product  is  condensed  sufficiently  to  contain  over 
24  per  cent  solids." 

When  the  milk  is  drawn  from  the  condensing  pan  it  is 
ready  to  be  canned,  but  as  this  requires  some  time,  the 
milk  is  first  cooled  to  prevent  acid  development  and  other 
fermentations.  The  cooling  is  usually  accomplished  by 
means  of  a  coil  in  a  manner  similar  to  that  of  cooling  fresh 
milk  in  a  city  milk  plant.  The  cooled  milk  is  stored  in 
sanitary  tanks,  drawn  out  a  little  at  a  time,  and  run  into 
the  can  fillers,  which  are  operated  in  a  manner  similar  to 
the  operation  of  the  common  milk-bottle  filler.  The  can- 
ning process  is  completed  with  the  soldering  on  of  the 
tops. 

Sterilization.  —  This  canned  evaporated  milk  quickly 
undergoes  fermentation  unless  absolutely  sterilized.  In 
order  to  effect  sterilization  it  is  necessary  to  heat  the  milk 
under  steam  pressure.  The  sterilizers  used  are  similar  in 
construction  and  principle  to  the  autoclave  used  in  the 
bacteriology  laboratory,  except  that  they  are  larger.  They 
are  so  arranged  that  trucks  loaded  with  cases  of  milk  may 
be  run  into  them  on  a  track. 

The  degree  of  heat  employed  and  the  duration  of  the 
heat  exposure  of  the  condensed  milk  are  very  important 
factors.  Even  perfectly  sweet,  normal  milk  curdles  at  a 
temperature  of  269°  F.,  and  the  more  concentrated  the 
milk  the  lower  the  temperature  required  to  curdle  it. 
There  are  other  factors,  such  as  the  per  cent  of  casein 
present,  the  relative  amounts  of  the  different  ash  con- 
stituents, etc.,  which  influence,  to  a  greater  or  less  degree, 
the  curdling  point  of  milk.  Temperatures  ranging  from 
226°  to  245°  F.  are  used  to  sterilize  condensed  milk. 


260 


DAIRY  TECHNOLOGY! 


The  greater  the  degree  of  heat,  and  the  longer  the  ex- 
posure, the  more  intense  is  the  action  on  the  condensed 
milk,  and,  therefore,  the  harder  the  coagulum  formed. 
Since  absolute  sterility  of  the  milk  is  necessary,  and  since 
heat  is  the  only  agent  that  can  be  used  to  bring  this  con- 
dition about,  the  milk  must  be  exposed  to  such  degree  of 
heat,  and  such  duration  of  that  heat  as  will  accomplish 
complete  sterilization. 

Shaking  the  Canned  Milk.  —  The  condensed  milk  hav- 
ing been  sterilized  in  sealed  cans,  the  next  process  in  order 


FIG.  48.  —  Combined  machine  for  sterilizing  and  shaking  condensed  milk. 

is  the  shaking  of  the  cans  to  break  any  lumps  of  curd  or 
fat  that  may  have  formed,  and  to  insure  a  smooth,  homo- 
geneous mixing  of  the  fat.  The  shaking  machine  may  be 
combined  with  the  sterilizer  or  it  may  be  a  separate  piece 
of  apparatus. 

After  the  shaking  process,  the  cans  are  placed  in  the 
testing  room,  or  incubator,  as  it  might  be  called,  where 
they  are  kept  at  about  blood  heat  for  several  days.  If 
any  live  spores  are  present  in  the  milk,  they  will  germinate 


CONDENSED  AND   EVAPORATED   MILK 


261 


and  multiply  rapidly  at  this  high  temperature.  Any  cans 
of  milk  that  have  fermented  are  readily  detected  on  account 
of  distended  sides  and  are  thrown  out  when  the  cans  are 
removed  from  the  store-room.  The  cans  are  so  arranged 
that  the  oldest  ones  can  be  removed  first. 

Composition  of  Evaporated  Milk.  —  When  milk  is  con- 
centrated in  the  ratio  of  two  parts  of  fresh  milk  to  one  part 
of  condensed  milk,  it  is  evident  that  the  percentage  of  the 
various  milk  constituents  in  the  evaporated  product  would 
be  just  double  that  in  the  fresh  milk. 

The  following,  from  Leach,  is  a  fair  example  of  a  good 
quality  of  evaporated  milk :  :. 


Total 
solids. 

Water. 

Milk 
sugar. 

Proteids. 

Fat. 

Ash. 

Number 
of  times 
condensed. 

28.16 

69.24 

9-85 

8.66 

8.1 

i-5S 

2.2 

Composition  of  Sweetened  Condensed  Milk.  —  In  the 

manufacture  of  sweetened  condensed  milk,  the  process 
employed  is  similar  to  that  used  in  the  production  of 
evaporated  milk.  The  great  difference  is  the  addition  of 
cane  sugar.  This  addition  of  cane  sugar  obviates  the 
necessity  for  sterilization  and  hence  enables  the  manu- 
facturer to  omit  that  very  delicate  process. 

Another  difference  between  evaporated  and  sweetened 
condensed  milk  is  that  the  latter  is  carried  to  a  greater 
degree  of  concentration,  commonly  32  per  cent  of  milk  solids 
and  often  more  than  this.  When  milk  is  too  thin  the  sugar 
deposits  in  the  bottom  of  the  cans,  and  this  greatly  de- 
creases its  commercial  value.  The  greater  the  degree  of 
concentration,  the  better  are  the  keeping  qualities.  Thin 
milk  is  more  prone  to  undergo  fermentation  than  the  highly 


262 


DAIRY  TECHNOLOGY 


concentrated  product.  Hence  we  find  sweetened  con- 
densed milk  usually  concentrated  in  the  proportion  of  two 
and  three-fourths  to  one. 

The  composition  of  this  product  varies  between  wide 
limits,  but  a  fair  example  of  a  good  quality  of  sweetened 
condensed  milk  is,  according  to  Leach,  as  follows: 


Total 
solids. 

Water. 

Milk 
solids. 

Cane 
sugar. 

Milk 
sugar. 

Proteids. 

Fat. 

Ash. 

Number 
of  times 
condensed. 

74.29 

2S-7I 

32.37 

41.92 

11.97 

8.46 

10.65 

1  .  29 

2-3 

Relatively  Large  Investment  Needed.  —  The  establish- 
ment and  operation  of  a  milk  condensery  is  a  much  larger 
proposition  than  the  manufacture  of  butter  or  cheese. 
More  milk  is  also  necessary  within  a  given  radius.  A 
condensing  plant  is  usually  not  very  prosperous  unless 
there  is  a  milk  supply  of  50,000  pounds  per  day.  An  ex- 
pensive building  and  expensive  machinery  are  required. 
A  good  supply  of  cold  water  is  a  requisite.  Roughly  speak- 
ing, a  supply  of  ten  times  as  much  water  as  there  is  milk 
to  be  condensed  should  be  assured.  The  steam  required 
is  also  a  large  item.  For  each  1000  pounds  of  milk  to  be 
condensed  per  day,  about  six  horse  power  of  steam  is 
needed.  However,  the  profits  are  proportionately  great, 
and  a  properly  conducted  factory  with  an  ample  supply 
of  milk  usually  prospers. 

The  large  condensery  finds  it  economical  to  use  all 
possible  labor-saving  devices.  Cases  are  nailed  with  a 
nailing  machine  and  the  labeling  is  done  automatically. 
Cans  are  fed  in  at  one  end  of  the  labeling  machines,  are 
carried  along,  a  label  is  pasted  on,  and  the  cans  are  delivered 
at  the  other  end  directly  into  the  shipping  cases  without 
further  handling. 


CONDENSED   AND   EVAPORATED   MILK  263 

However,  milk  condensing  as  a  side  line  for  the  ice- 
cream manufacturer,  city  milk  dealer,  and  creamery  man 
has  been  adopted  in  a  few  instances.  Machinery  is  on 
the  market  for  condensing  as  small  quantities  as  250  to 
6000  pounds  of  fresh  milk  daily.  This  apparatus  may  be 
installed  for  about  one  thousand  dollars,  and  may  be  of 
value  in  turning  surplus  milk  into  bulk,  condensed  milk, 
provided  a  market  for  this  product  is  assured. 


t 
CHAPTER  XXX. 

MILK  POWDER. 

SOME  economist  has  calculated  that  because  milk  is 
nearly  nine-tenths  water  the  transportation  of  this  natural 
product  costs  ten  times  as  much  as  it  should.  Figuring 
on  a  basis  of  2,000,000  quarts  per  day  as  New  York  City's 
daily  milk  supply,  he  finds  that  the  people  are  losing  about 
$17,500  per  day.  This  is  the  expense  of  the  shipping, 
carting,  hauling,  bottling,  etc.,  of  the  watery  portion  of  the 
milk.  This  means  an  annual  loss,  in  N.  Y.,  of  $6,500,000 
from  this  source.  On  this  basis  the  national  loss  is  esti- 
mated to  be  about  $63,000,000  per  annum. 

Without  accepting  or  discussing  the  accuracy  of  the 
above  calculations,  or  the  necessity  for  bringing  to  the 
consumer  a  natural,  uncondensed  product,  we  must  admit 
that  there  are  many  places  where  a  good  concentrated 
milk  could  replace  the  bulky  natural  product,  and  where 
milk  in  that  form  would  be  and  is  used  when  the  natu- 
ral milk  cannot  possibly  be  utilized. 

One  pound  of  condensed  or  evaporated  milk  represents 
but  two  to  two  and  one-half  pounds  of  raw  milk,  while  one 
pound  of  milk  powder  represents  about  eight  pounds  of 
natural  milk. 

Advantages  of  Milk  Powder.  —  The  chief  desirable 
results  of  reducing  milk  to  powder  may  be  summed  up  as 
follows.  This  refers  to  milk  powder  made  from  skim  milk. 

i.  It  is  concentrated,  making  cost  of  package  and  trans- 
portation the  minimum. 

264 


MILK  POWDER  265 

2.  It  has  good  keeping  properties.     Germs  do  not  multi- 
ply in  skim-milk  powder,  even  at  ordinary  room  temper- 
ature. 

3.  It  is  a  dry  substance,  making  it  handy  to  carry  on 
long  sea  and  land  journeys. 

4.  A  milk  of  any  consistency  or  richness  can  be  made 
from  it  by  adding  water,  making  it  of  special  value  in 
baking,  candy  making,  and  ice-cream  manufacture. 

History  and  Development  of  Milk  Desiccation.  —  The 
problem  of  inventing  a  proper  system  of  milk  desiccation 
has  been  worked  upon  to  some  extent  for  more  than  a 
century,  but  more  especially  during  the  past  sixty  years. 

As  early  as  1810,  a  man  by  the  name  of  Appert  produced 
milk  tablets,  but  they  did  not  become  of  any  commercial 
importance.  In  1856  a  Mr.  Grimwade  published  a  method 
of  manufacturing  dried  milk.  It  consisted  of  sweetening 
the  milk  with  sugar  and  at  the  same  time  adding  carbonate 
of  soda.  These  substances  were  added  to  produce  granu- 
lation in  the  latter  stages  of  dryness.  This  mixture  was 
put  into  a  jacketed  pan,  which  was  pivoted  and  kept  in 
constant  motion  during  time  of  drying.  The  surrounding 
jacket  was  filled  with  hot  water,  the  temperature  of  which 
never  went  above  i29°F.  When  the  mixture  became 
pasty,  it  was  poured  off  into  smaller  pans,  stirred  and 
dried  still  more;  then  this  paste  or  dough  was  passed 
between  marble  rollers  and  pressed  into  thin  sheets.  These 
sheets  were  then  dried  with  hot  air  and  finally  ground  to 
powder.  Later  the  vacuum  pan  was  used  in  condensing. 

Another  process  consisted  of  precipitating  the  casein 
and  fat  by  the  use  of  acetic  acid  or  rennet.  This  curd 
was  drained  and  then  dried  on  plates  at  a  temperature 
of  between  i2o°F.  and  160°  F.  The  solubility  of  this 
powder  was  restored  by  adding  a  little  soda.  The  widely 


266  DAIRY  TECHNOLOGY 

advertised  "  plasmon  "  is  made  in  this  manner.  The 
process  was  not  economical  as  some  of  the  milk  nutrients 
(sugar  and  albumen)  were  lost  in  the  whey.  This  sub- 
stance (plasmon)  does  not  contain  all  of  the  elements 
of  milk,  and  therefore  could  not  serve  as  a  substitute  for 
milk. 

Milk  powder  became  of  commercial  importance  when 
the  Just-Hatmaker  machine  and  process  of  drying  came 
into  use.  The  patent  for  this  process  is  dated  May  23, 
1902.  The  desiccating  machine  consists  of  two  large 
revolving  polished  rollers  or  cylinders  placed  parallel  in 
a  frame.  The  rollers  are  about  sixty  inches  in  length 
and  twenty-eight  inches  in  diameter.  They  revolve  in 
opposite  directions  at  about  six  revolutions  per  minute. 
Steam  is  introduced  through  the  end  of  the  spindle  and 
a  pressure  of  40  pounds  is  maintained.  This  insures  a 
constant  temperature  of  285°  F.  The  condensed  steam 
is  removed  at  the  other  end  at  the  corresponding  place. 

The  two  cylinders  are  about  one  eighth  of  an  inch  apart. 
When  the  milk  falls  and  spreads  in  thin  sheets  on  these 
revolving  hot  cylinders,  it  dries  almost  instantaneously. 
The  residue  remains  on  the  cylinders  and  is  scraped  off  in 
a  powder-like  consistency  by  means  of  scrapers  attached 
to  the  machine.  The  powder  is  now  passed  through  a 
fine  sieve  and  is  then  ready  for  packing. 

Drs.  George  Doellner,  Buttler  and  J.  Maggo  have  all 
patented  homogenization  of  the  milk  previous  to  dry- 
ing. It  is  claimed  that  this  improves  the  keeping  prop- 
erty. The  process  reduces  the  size  of  the  fat  globules  to 
such  an  extent  that  decomposition  proceeds  very  slowly. 
This  latter,  however,  is  by  no  means  a  well-established  fact. 

Dr.  Eckenberg  of  Sweden  has  invented  an  ingenious 
system  of  milk  drying  at  a  low  temperature  and  in  vacuum. 


MILK  POWDER  267 

The  machine  consists  of  a  cylindrical  device  inside  of 
which  rotates  slowly  a  nickel-plated  drum.  The  interior 
of  the  drum  is  steam-heated.  An  air  pump  creates  a 
vacuum.  The  milk  is  put  into  the  bottom.  The  ro- 
tating drum  picks  up  a  film  of  the  milk  and  dries  it  prac- 
tically instantaneously,  although  the  temperature  is  only 
about  104°  F. 

Scrapers  take  off  the  dried  milk  from  the  drum  and 
discharge  it  into  a  receiver  on  the  side,  through  valves 
which  open  and  close  intermittently. 

The  Modern  Method.  —  A  description  of  the  latest 
and,  so  far  as  known,  the  most  successful  method  of  milk 
desiccation  is  given  by  L.  C.  Merrell  in  a  paper  read 
before  the  Syracuse  Section  of  the  American  Chemical 
Society,  1908. 

"  Fresh  whole  milk  is  drawn  into  a  vacuum  pan  and  a 
portion  of  its  water  removed.  This  condensation  is  halted 
while  the  milk  is  still  in  a  fluid  condition  and  before  any 
of  the  milk  albumen  has  been  cooked  on  to  the  walls  of 
the  vacuum  chamber.  The  milk  is  then  drawn  from  the 
vacuum  pan  and  sprayed  into  a  current  of  hot  air.  The 
moisture  of  the  milk  is  instantly  absorbed  by  the  air  and 
the  particles  of  milk  solids  fall  like  snow.  Upon  exami- 
nation, they  are  found  to  contain  less  than  two  per  cent  of 
moisture.  The  hotter  the  air  is,  the  more  rapid  the  dry- 
ing effect  and  the  less  danger  there  is  of  injuring  the  milk 
solids  by  heat. 

"  This  method  of  desiccation  does  not  destroy  the  globu- 
lar condition  of  the  butter  fat,  it  does  not  burn  the  milk 
sugar,  nor  does  it  coagulate  the  albumen  of  the  milk.  It 
is  not  necessary  to  neutralize  the  acidity  of  the  milk,  for 
the  moisture  is  removed  so  quickly  that  there  is  no  chance 
for  chemical  action,  and  neither  the  casein  nor  the  albumen 
is  effected  in  any  way  by  the  concentration  of  the  acid. 
The  difficult  pasty  condition  of  the  milk  solids  is  passed 
while  the  milk  particle  is  suspended  in  the  air  and  not  in 


268  DAIRY  TECHNOLOGY 

contact  with  heated  metal.  As  nearly  as  I  can  estimate, 
one  pint  of  milk  presents  about  two  acres  of  surface  when 
sprayed  into  the  air.  The  individual  dried  particles  are 
from  one  two-thousandth  to  one  ten-thousandth  of  an 
inch  in  diameter. 

"  No  bacterial  action  has  been  discovered  in  milk  powder 
containing  less  than  3  per  cent  moisture,  and  no  chemical 
deterioration  takes  place.  It  is,  therefore,  evident  that 
the  milk  powder  product  described  above  fulfills  my 
definition  of  an  ideal  preserved  milk,  for  decomposition  is 
prevented  merely  by  dryness  and  without  the  use  of  pre- 
servative substances  and  without  changing  the  chemical 
composition  of  the  milk.  This  whole  milk  powder  is  in 
use  in  place  of  fresh  milk  at  several  of  the  United  States 
soldiers'  homes  and  military  posts  as  well  as  in  the  navy. 
It  has  been  subjected  to  the  most  exhaustive  tests  by  the 
United  States  Department  of  Agriculture,  Bureau  of  Chem- 
istry, and  by  the  Experiment  Stations  of  different  states. 
The  Pacific  fleet  carried  a  ton  of  it  around  the  Horn  under 
an  absolute  guaranty  as  to  keeping  quality  and  has  since 
re-ordered  largely.  A  10  cent  package  makes  one  and  a 
half  quarts  of  milk,  at  $o.o6f  a  quart.  With  these  re- 
sults in  mind  it  is  not  too  much  to  assume  that  the  reduc- 
tion of  milk  to  powder  offers  a  satisfactory  solution  of  the 
universal  milk  question." 

Use  of  Milk  Powder.  —  This  product  is  being  used  to 
replace  fresh  milk  by  bakers,  confectioners  and  ice-cream 
manufacturers.  It  was  used  as  a  food  by  the  Shackle  ton 
South  Polar  expedition,  and  was  one  of  the  main  foods  of 
the  party  that  reached  the  magnetic  pole. 

The  authors  1  have  found  milk  powder  to  be  of  great 
value  for  starter-making  purposes  in  creameries  so  located 
that  a  supply  of  fresh  milk  is  not  easily  obtainable. 

The  milk  powder  was  dissolved  in  pure  water,  making 
a  lo-per-cent  solution.  Pasteurization,  inoculation,  ripen- 

1  So.  Dakota  Bui.,  No.  123. 


MILK  POWDER 


269 


ing,  etc.,  of  the  milk-powder  starters  were  all  carried  on 
in  the  same  manner  as  when  fresh-milk  starters  were 
made  and  the  results  secured  by  the  use  of  milk-powder 
starters  were  as  good  as  those  when  fresh-milk  starters 
were  used. 

Milk  powder  is  used  in  the  preparation  of  commercial 
cultures  of  lactic-acid  bacteria,  the  culture  material  being 
mixed  with  sterile-milk  powder,  bottled  and  distributed 
for  use  in  butter  and  cheese  factories.  In  this  medium 
the  lactic  bacteria  retain  their  vitality  for  more  than  a 
year. 

Composition.  —  Three  kinds  of  milk  powders  are  manu- 
factured: whole-milk  powder,  half-skimmed- milk  powder 
and  skimmed-milk  powder.  The  butter  fat  in  the  whole- 
milk  powder  interferes  with  its  keeping  properties. 

The  composition  of  these  dried  milks  is  as  follows: 


Whole  milk. 

Half-skimmed. 

Skimmed. 

Casein  

Per  cent. 
26  .92 

Percent. 
VH  •  3O 

Per  cent. 
37   OO 

Milk  sugar  
Butter  fat  
Milk  salts  (ash)  

36.48 
29.  2O 
6  .00 

39-70 
15.10 
6  .90 

47.00 
1.  00 

8.00 

Moisture  

i  40  . 

5  oo 

7.00 

Whey  Powder  or  Dried  Whey.  —  Whey  is  reduced  to 
a  powder  by  exactly  the  same  process  as  that  employed 
in  the  reduction  of  milk  to  powder.  This  powder  is 
used  in  the  diet  of  infants  and  invalids,  in  cases  where 
the  presence  of  casein  interferes  with  proper  digestion. 
Many  dietary  formulas  call  for  whey  as  one  of  the  ingre- 
dients. Fresh  whey  is  not  always  obtainable,  but  whey 
powder  may  be  kept  on  hand  at  all  times  and  is  ready  for 
use  upon  the  addition  of  water. 


CHAPTER  XXXI. 

RENOVATED  BUTTER. 

STATISTICS  show  that  more  than  a  billion  pounds  of  butter 
are  made  on  farms  in  this  country  every  year.  Some  of 
it  is  consumed  at  home,  but  most  of  it  is  taken  to  the  local 
grocer.  Of  this  latter,  the  best  grades  usually  find  ready 
sale  to  consumers  in  town.  Unfortunately,  dairy  butter 
varies  so  greatly  in  quality,  and  so  much  of  it  is  poor, 
that  vast  quantities  of  this  product  are  unsalable  as 
butter. 

The  production  of  farm  butter  is  much  greater  during 
the  summer  than  it  is  during  the  winter.  This  results  in 
an  overproduction  during  the  hot  summer  months,  when  it 
is  difficult  to  control  quality,  under  average  farm  condi- 
tions. As  a  consequence,  much  of  it  is  finally  marketed 
at  the  renovating  plant. 

Ladles.  —  The  chief  method  of  disposing  of  this  farm 
butter  in  the  past  was  to  add  color  and  salt  if  needed,  and 
work  it  into  a  homogeneous  product.  This  reworking  con- 
verted the  various  colors  and  qualities  of  butter  into  one 
batch  having  a  uniform  color,  degree  of  saltiness,  and 
quality.  Heavy  salting  was  usually  practiced  to  conceal 
the  undesirable  flavors.  This  reworked  butter  is  known 
commercially  as  ladles  or  ladled  butter.  Only  the  best 
farm  butter,  of  most  uniform  color  and  salt  content,  is 
now  used  for  ladles.  The  remainder  is  manufactured  into 
renovated  or  process  butter. 

270 


RENOVATED   BUTTER  271 

Origin  of  Renovated  Butter.  —  The  chief  drawbacks  to 
ladled  butter  was  that  the  bad  flavors  were  still  in  the 
finished  product,  and  the  body  was  weak.  This  gave 
rise,  in  the  early  eighties,  to  some  experiments  for  the  pur- 
pose of  finding  a  method  of  eliminating  the  bad  flavors 
from  the  raw  product. 

Melting  butter,  separating  out  and  canning  the  fat  for 
use  in  tropical  countries,  had  been  practiced  in  some  sec- 
tions of  Europe  for  many  years;  but  recovering  the  pure 
butter  fat  and  again  converting  this  substance  into  butter 
is  an  American  invention.  In  1883  butter  was  renovated 
by  this  method  in  Memphis,  Missouri. 

In  the  early  nineties  renovated  butter  began  to  appear 
in  considerable  quantities  on  the  markets  of  this  country. 
It  was  commonly  sold  as  creamery  butter,  usually  as 
"  seconds,"  but  in  time  of  scarcity  of  creamery  butter 
some  of  the  best  grades  would  sell  as  "  creamery  extras." 
In  Philadelphia  it  was  often  called  "  boiled  "  butter,  and 
in  Boston,  "  sterilized  "  butter. 

In  1897  the  dairy  and  food  commissioner  of  Pennsyl- 
vania attempted  in  a  legal  way  to  compel  a  manufacturer 
of  renovated  butter  in  Philadelphia  to  sell  his  product 
for  what  it  was,  instead  of  selling  it  as  creamery  butter. 
This  company  finally  agreed  to  discontinue  selling  its 
product  as  creamery  butter,  and  to  print  on  the  wrap- 
pers a  name  satisfactory  to  the  commissioner.  The  name 
"  renovated  "  was  selected  as  most  proper  for  defining 
this  product.  This  name  has  been  generally  adopted, 
but  the  name  "  process  "  butter  is  used  synonymously 
with  it. 

Extent  of  the  Industry.  —  In  1905,  78  factories  were 
manufacturing  renovated  butter.  Each  factory  has  its 
own  system,  which  the  operator  claims  is  superior  to  any 


272  DAIRY  TECHNOLOGY 

other  system;  but  the  general  process  is  similar  in  all 
cases,  the  differences  being  in  the  details  only. 

These  factories  manufacture  about  60,000,000  pounds 
of  renovated  butter  per  annum. 

Only  the  best  grades  of  packing  stock  are  used  in  this 
product;  the  manufacturers  have  learned  that  it  is  im- 
possible to  make  a  marketable  article  from  old  rancid 
stock.  Such  material  is  of  value  only  when  used  for  soap- 
grease. 

The  tendency  to-day  is  toward  selling  cream  from  the 
farm;  while  some  years  ago  it  was  largely  made  into  butter 
which  finally  went  to  the  renovating  factories.  The  former 
method  is  more  profitable  and  handier  to  the  farmer,  and 
is  more  in  accordance  with  general  economical  principles. 

The  Processes  of  Manufacture. 

Melting.  —  The  butter  is  brought  into  the  factory  in 
barrels  and  dumped  into  the  melting  tank.  These  melt- 
ing tanks  are  of  many  different  designs,  one  form  of  which 
is  a  tank  having  a  coil  near  the  bottom  through  which 
passes  hot  water.  The  vat  is  also  jacketed  and  surrounded 
with  hot  water.  The  butter  is  emptied  from  the  barrels 
into  the  vat,  where  it  remains  until  completely  melted; 
then  the  butter-fat  oil  is  run  out  at  one  end  through  a 
strainer  to  remove  the  paper,  wood  and  other  foreign 
matter  occasionally  found  in  the  raw  material.  As  this  oil 
runs  from  the  vat  and  through  the  strainer  it  is  pumped 
into  steam-jacketed,  cylindrical  iron  tanks,  where  it  is 
held  at  a  temperature  of  about  i2o°F.  for  two  to  three 
hours  to  permit  the  curd  to  settle  out.  This  "  slush,"  as 
the  settlings  are  called,  is  drawn  out  through  a  valve  at 
the  bottom  of  the  tank,  and  run  through  an  old-style, 


RENOVATED  BUTTER  273 

hollow-bowl,  Danish- Weston  separator,  and  the  recovered 
oil  added  to  the  main  batch. 

Refining  the  Oil.  —  This  clear  oil  is  run  into  a  second  set 
of  tanks,  or  kettles,  kept  at  a  constant  temperature  of 
about  i20°F.  for  several  hours.  During  this  time,  pure, 
hot  air  is  continuously  pumped  through  the  fat.  The  air  is 
conducted  to  the  bottom  of  the  kettle  through  a  pipe  ex- 
tending through  the  oil  from  the  top.  This  air  rises  and 
causes  a  constant  ebullition  of  the  oil.  This  aeration  at  a 
high  temperature  removes  practically  all  the  bad  odors  and 
flavors,  and  leaves  an  almost  tasteless,  clear,  yellow  oil. 

Making  the  Emulsion.  —  This  oil  is  emulsified  with  sour 
milk,  in  order  to  reincorporate  into  it  a  natural  butter 
flavor  and  the  components  of  normal  butter.  For  this 
purpose  a  quantity  of  good  fresh  skim  milk  is  ripened  with 
a  commercial  culture  of  lactic-acid  bacteria,  just  as  a  starter 
is  made  in  a  butter  or  cheese  factory.  To  this  sour  milk 
is  added  about  twice  its  volume  of  sweet  skim  milk;  then 
this  mixed  milk  is  added  to  the  molten  oil  in  the  ratio  of 
about  one  part  milk  to  one  and  one-half  parts  oil.  The 
milk  and  oil  are  mixed  and  emulsified  in  a  cylindrical  tank 
or  kettle  in  which  there  is  a  rapidly  revolving  dasher.  In 
some  factories  the  emulsion  is  made  in  the  same  kettle 
in  which  the  renovating  process  occurred.  The  mixing  is 
accomplished  by  passing  air  through  the  mixture. 

Crystallizing  the  Fat.  —  This  emulsion  is  then  run  into  a 
large  vat  of  water  at  a  temperature  of  36°  to  46°  F.,  which 
crystallizes  the  fat.  Even  though  such  a  large  percentage 
of  milk  is  present  it  is  all  incorporated  in  the  fat  crystals. 
The  water  shows  no  trace  of  milkiness. 

The  crystallizing  vat  is  usually  placed  directly  under- 
neath the  bottom  of  the  renovating  or  mixing  kettle.  This 
latter  tapers  at  the  bottom  to  a  small  mouth.  A  valve  at 


274  DAIRY  TECHNOLOGY 

this  place  enables  the  operator  to  govern  the  size  or  amount 
of  fat  that  runs  into  the  crystallizing  tank.  The  water 
used  in  the  crystallizing  process  is  kept  cold  by  the  use  of 
crushed  ice  or  by  mechanical  refrigeration. 

The  butter  crystals  are  scooped  from  the  surface  of  the 
water,  piled  on  trays  or  trucks  and  run  into  a  cooler  to 
drain  and  ripen  over  night.  Holding  this  for  several  hours 
at  a  low  temperature  before  salting  and  working  improves 
the  body  of  the  final  product  and  enables  the  fat  to  absorb 
the  milky  flavors. 

Working  and  Salting.  —  On  the  following  morning,  the 
butter  granules  are  put  into  a  combined  churn  and  worker, 
worked  in  brine  several  revolutions  to  work  out  the  excess 
of  buttermilk,  then  drained,  dry-salted,  worked  until  the 
salt  is  dissolved,  and  finally  removed  from  the  churn  and 
packed  into  tubs,  62^  pounds  being  weighed  into  each  tub. 

The  word  "  Process  "  or  "  Renovated  "  is  imprinted  in 
the  butter  and  also  marked  on  the  outside  of  the  tub  in 
accordance  with  the  requirements  of  Internal  Revenue 
Department.  As  the  flavor  of  the  butter  is  better  when  a 
week  old  than  when  fresh  it  is  usually  kept  in  the  refrigerator 
several  days  before  it  is  shipped  out. 

Extracts  from  United  States  Laws  Relating  to  Reno- 
vated Butter.  —  "  Manufacturers  of  process  or  renovated 
butter  shall  pay  a  special  tax  of  $50  per  year,  and  manu- 
facturers of  adulterated  butter  shall  pay  $600  per  year. 
Every  person  who  engages  in  the  production  of  process 
or  renovated  butter  or  adulterated  butter  as  a  business 
shall  be  considered  to  be  a  manufacturer  thereof. 

That  every  person  who  carries  on  the  business  of  manu- 
facturer of  process  or  renovated  butter  or  adulterated 
butter  without  having  paid  the  special  tax  therefor,  as 
required  by  law,  shall,  besides  being  liable  to  the  payment 
of  the  tax,  be  fined  not  less  than  $1000  and  not  more  than 


RENOVATED   BUTTER  275 

$5000;  and  every  person  who  carries  on  the  business  of 
a  dealer  in  adulterated  butter  without  having  paid  the 
special  tax  therefor,  as  required  by  law,  shall,  besides 
being  liable  to  the  payment  of  the  tax,  be  fined  not  less 
than  $50  nor  more  than  $500  for  each  offense. 

That  every  manufacturer  of  process  or  renovated  butter 
or  adulterated  butter  shall  file  with  the  collector  of  inter- 
nal revenue  of  the  district  in  which  his  manufactory  is 
located  such  notices,  inventories,  and  bonds,  shall  keep 
such  books  and  render  such  returns  of  material  and  prod- 
ucts, shall  put  up  signs  and  affix  such  number  of  his 
factory,  and  conduct  his  business  under  such  surveillance 
of  officers  and  agents  as  the  Commissioner  of  Internal 
Revenue,  with  the  approval  of  the  Secretary  of  the  Treas- 
ury, may  by  regulation  require.  But  the  bond  required 
of  such  manufacturer  shall  be  with  sureties  satisfactory 
to  the  collector  of  internal  revenue,  and  in  a  penal  sum 
of  not  less  than  $500;  and  the  sum  of  said  bond  may  be 
increased  from  time  to  time  and  additional  sureties  re- 
quired at  the  discretion  of  the  collector  or  under  instruc- 
tions of  the  Commissioner  of  Internal  Revenue. 

Renovated  butter  having  16  per  cent  or  more  of  moisture 
will  be  held  to  contain  '  abnormal  quantities  of  water, 
milk  or  cream/  and  be,  therefore,  classed  as  '  adulterated 
butter.' 

All  renovated  butter  may  be  packed  by  the  manufac- 
turer thereof  in  firkins,  tubs,  or  packages  of  wood  or  other 
suitable  material  not  before  used  for  that  purpose ;  but 
each  package  must  contain  not  less  than  10  pounds;  and, 
when  packed  in  a  solid  body  or  mass,  there  shall  be  stamped 
or  branded  into  the  upper  surface  of  the  butter  the  words 
'  Renovated  Butter  '  in  one  or  two  lines,  the  letters  to 
be  gothic  style,  not  less  than  one-half  inch  square  and 
depressed  not  less  than  one-eighth  inch. 

Manufacturers  will  be  permitted  to  pack  prints,  bricks, 
or  rolls  of  renovated  butter  not  less  than  one  pound  in 
weight;  but  each  print,  brick,  or  roll  must  have  stamped 
thereon  the  words  '  Renovated  Butter '  in  two  lines, 
the  letters  to  be  depressed,  of  gothic  style,  not  less  than 


276  DAIRY  TECHNOLOGY 

three-eighths  inch  square  and  sunken  not  less  than  one- 
eighth  inch.  The  contents  of  any  package  less  than  ten 
pounds  will  be  considered  as  a  brick  or  roll." 

Test  for  Renovated  Butter. 

Spoon  Test.  —  Heat  about  five  grams  of  the  sample  to 
be  tested  in  a  large  spoon  over  a  small  flame.  Genuine 
butter  will  boil  quietly,  but  with  the  production  of  con- 
siderable froth  and  foam.  Renovated  butter  or  oleo- 
margarine will  sputter  noisily,  but  will  not  foam  much. 
The  curd  in  the  former  will  be  small  and  finely  divided: 
while  in  the  latter  it  will  be  found  in  larger  masses  or  lumps. 

To  distinguish  renovated  butter  from  oleomargarine 
it  is  necessary  to  use  the  butyro-refractometer  or  the 
chemical  tests  as  described  under  "  Oleomargarine." 


-  CHAPTER  XXXII. 

OLEOMARGARINE. 

OLEOMARGARINE,  Butterine,  Dutch  Butter  and  Mar- 
garine are  terms  that  are  used  synonymously.  All  refer 
to  articles  which  are  manufactured  as  butter  substitutes. 
They  are  all  made  chiefly  from  beef  fat,  and  are  made 
to  imitate  butter  as  nearly  as  possible.  To  some  of  the 
better  grades  (as  butterine),  a  definite  amount  of  real 
butter  or  cream  is  added.  Beef  fat  is  chiefly  composed 
of  tissue  and  fats  belonging  to  the  non-volatile  and  in- 
soluble group,  such  as  stearin,  palmatin  and  olein.  The 
chief  difference  between  butter  and  margarine  is  that  the 
butter  contains  fats  of  the  lower  series  which  belong  to 
the  volatile  and  soluble  group,  of  which  butyrin  is  the 
chief  one.  Margarine  does  not  contain  any  noticeable 
amount  of  the  volatile  fats  unless  butter  has  been  added, 
as  is  sometimes  the  case.  Oleomargarine  is  therefore  not 
a  dairy  product,  but  is  briefly  mentioned  here  because  dairy 
products  are  used  in  connection  with  its  manufacture. 

Origin  of  Margarine.  —  According  to  history,  marga- 
rine was  first  manufactured  in  France.  It  is  said  that  a 
French  chemist  named  M.  Mege-Mourier  was  requested 
by  the  French  Emperor,  Napoleon  III,  to  investigate  the 
problem  of  getting  a  good,  wholesome  and  cheap  substi- 
tute for  butter.  This  was  evidently  done  to  reduce  the 
expenses  during  the  France-German  war  of  1870.  In 
a  short  time  he  had  prepared  a  quality  of  goods  which 
resembled  butter  to  such  an  extent  that  it  required  an 

277 


278  DAIRY  TECHNOLOGY 

expert  to  distinguish  it  from  that  product.  The  new 
article  was  named  after  the  discoverer  and  the  fat  from 
which  it  was  made,  viz.,  "  Margarine-Mourier."  The 
new  substitute  for  butter  had  many  good  qualities,  and 
could  be  prepared  from  ox  tallow  in  a  very  simple  way. 

The  Paris  Health  Counsel  on  April  12,  1872,  admitted 
the  sale  of  the  new  fat,  provided  it  was  not  brought  into 
the  commercial  market  under  the  name  of  "  butter." 

The  Original  Process.  —  The  process  which  M.  Mourier 
used  was  an  excellent  one.  Nothing  but  the  very  best 
of  fat  was  used.  The  stearin  was  separated  from  it,  thus 
leaving  a  fat  with  a  relatively  low  melting-point,  similar 
in  that  respect  to  butter.  The  raw  fat  possessed  a  pe- 
culiar and  undesirable  animal  taste  which  his  particular 
process  of  manufacture  eliminated. 

The  thoroughly  washed  and  finely  chopped  fat  was  put 
into  a  tank.  For  every  1000  parts  of  fat,  300  parts  of 
water,  i  part  of  carbonate  of  potash  and  two  well-cleaned 
stomachs  of  pigs  or  sheep  were  added.  The  mixture  was 
held  at  a  temperature  of  113°  F.  for  a  few  hours  to  digest 
the  fatty  tissue.  It  was  then  allowed  to  cool  to  effect  the 
crystallization  of  the  stearin  and  palmatin,  after  which  it 
was  put  into  a  press.  The  term  "  oleomargarine  "  was 
applied  to  this  new  expressed  fat.  The  product  was  pure, 
wholesome  and  nutritious.  The  manufacture  of  it  soon 
became  an  established  industry  in  France,  America,  Ger- 
many, Austria,  Russia,  Holland  and  other  countries.  It 
was  an  excellent  cooking  fat,  containing  a  greater  per- 
centage of  fat,  and  possessing  better  keeping  qualities 
than  average  butter,  and  excelling  poor  butter  in  flavor. 

Developments  in  the  Industry.  —  The  result  of  this  ex- 
tended use  of  the  oleomargarine  was  that  not  enough 
raw  material  could  be  secured.  As  a  result,  the  ox  tallow, 


OLEOMARGARINE  279 

which  was  formerly  purified  and  melted  at  a  temperature 
of  113°  F.,  was  now  exposed  and  melted  at  140°  F.  This 
included  more  of  the  fats  having  a  high  melting-point,  in  the 
margarine  oil. 

This  new  process  overthrew  the  desirable  Mege-Mourier 
process  of  manufacture  of  oleomargarine.  According  to 
his  method,  100  pounds  of  raw  material  yielded  only  about 
twenty- two  pounds  of  margarine,  and,  according  to  the  new 
method,  100  pounds  of  a  raw  tallow  yielded  about  sixty- 
one  pounds.  The  latter  product,  however,  was  of  an  in- 
ferior quality.  It  was  more  solid  and  richer  in  stearin. 
It  had  a  melting-point  of  about  110°  F.,  which  was  a  very 
serious  objection  to  its  healthfulness. 

In  order  to  lower  the  melting-point  of  this  substance 
and  apparently  to  improve  its  usefulness,  the  cheaper  kinds 
of  vegetable  oils  were  used,  such  as  cottonseed  oil,  rape  oil, 
the  purer  grades  of  olive  oil,  sesame  oil,  cocoa  oil,  etc.  The 
increased  use  and  consequent  demand  for  oleomargarine 
forced  the  manufacturers  to  make  use  of  other  fats  than 
ox  tallow.  According  to  patents  taken  out  in  Europe,  the 
following  fats  were  used:  Bacon  fat,  goose  fat,  veal  tal- 
low, stearin  fat  from  soap  manufacturers,  slaughter  house 
fat  and  fat  from  flaying  houses.  Some  of  the  fats  had  a 
very  undesirable  smell,  and  were  purified  by  treating  with 
strong  mineral  acids. 

From  this  it  will  be  seen  that  oleomargarine  became  a 
cheap  adulterated  food.  In  the  face  of  this,  the  sale  and 
manufacture  of  it  continued  to  increase  and  became  very 
extensive.  Especially  was  this  so  in  the  United  States, 
where  in  the  large  cities,  at  the  big  slaughtering  houses, 
so  much  animal  fat  accumulated. 

Manufacture  of  Oleomargarine.  —  It  is  impossible  to 
describe  in  a  precise  detailed  form  each  specific  operation 


280  DAIRY  TECHNOLOGY 

which  the  raw  material  for  oleomargarine  must  undergo, 
because  the  processes  of  manufacture,  especially  in  the 
United  States,  are  considered  to  be  trade  secrets. 

The  caul  fat  of  freshly  killed  beeves  is,  after  a  thorough 
washing,  first  in  tepid  water,  then  in  ice  water,  allowed  to 
stand  in  a  cold  room  until  thoroughly  chilled.  It  is  then 
rendered  between  a  temperature  of  130°  and  175°  F.  The 
resulting  oil  is  allowed  to  cool  slowly  until  a  considerable 
portion  of  the  stearin  and  palmitin  has  crystallized  out. 
This  pasty  mass  is  then  subjected  to  hydraulic  pressure. 
The  oil  or  fluid  part  (about  two-thirds  of  the  whole)  flows 
out  into  a  tank  of  cold  water,  where  it  solidifies  into  a 
granulated  mass  known  to  the  trade  as  "  oleo  "  oil,  or 
simply  "  oleo."  The  name  "  oil  "  is  somewhat  misleading, 
as  the  product  is  a  granular  solid  of  a  dull  whitish  color. 
Fresh  leaf  fat  treated  in  exactly  the  same  way  as  the  beef 
tallow  yields  the  "  neutral  "  lard  or  "  neutral  "  of  the  trade, 
also  a  granular  solid  of  a  white  color. 

The  objects  of  this  treatment  are  twofold:  to  produce 
fats  as  free  as  possible  from  taste  and  odor ;  and  to  remove 
some  of  the  stearin  and  palmitin,  in  order  that  the  finished 
product  may  have  a  lower  melting-point. 

The  "  oleo  "  and  the  "  neutral  "  are  then  mixed.  The 
proportions  vary  according  to  the  marketing  place  of  the 
product  (a  warm  climate  calling  for  more  "oleo,"  a  cold 
one  for  more  "  neutral  ")  and  the  amount  of  butter  with 
which  the  mixture  is  flavored.  This  mixing  is  done  in 
large,  steam-jacketed  vessels  provided  with  revolving 
paddles,  by  which  their  contents  can  be  easily  mixed. 
Here  the  "  oleo  "  and  the  "  neutral "  are  thoroughly 
agitated  with  a  certain  proportion  of  milk  (soured  by  in- 
oculation with  a  pure  culture  of  lactic-acid  bacteria), 
and  sometimes  with  cream,  butter  and  cottonseed  oil, 


OLEOMARGARINE  281 

depending  upon  the  grades  of  the  product  to  be  manu- 
factured. 

Having  been  brought  into  a  perfect  emulsion,  the  mixture 
is  run  into  a  vat  of  ice  water,  which  causes  the  formation 
of  crystals  or  granules  of  fat  similar  to  small  granules  of 
butter,  such  as  are  formed  in  the  churning  of  cream. 

The  fat  granules  are  held  at  a  low  temperature  several 
hours  to  ripen,  then  put  into  a  churn,  worked  and  salted 
just  as  in  the  manufacture  of  renovated  butter. 

The  proportions  in  which  these  raw  materials  are  mixed 
are  given  by  the  i2th  Census  Report  of  the  United  States 
for  each  of  the  three  high  grades  of  oleomargarine  manu- 
factured as  follows:  High  grade, 

pounds . 
Oleo  oil 100 

Neutral  lard 130 

Butter 95 

Salt..... 32 

Color 00.5 

357-5 

will  produce  about  352  pounds  of  oleomargarine. 

Medium  high  grade, 

pounds. 
Oleo  oil 315 

Neutral  lard 500 

Cream • 280 

Milk 280 

Salt 120 

j    Color 1.5 

1496.5 

will  produce  from  1050  to  1080  pounds  of  oleomargarine. 

Cheap  grade, 
pounds. 

Oleo  oil 495 

Neutral  lard 265 

Cottonseed  oil 315 

Milk 255 

Salt 120 

Color 1.25 

1451-25 

will  produce  from  1265  to  1300  pounds  of  oleomargarine. 


282 


DAIRY  TECHNOLOGY 


The  following  formulas  are  taken  from  "  The  Modern 
Packing  House,"  by  F.  W.  Wilder,  former  general  super- 
intendent of  Swift  &  Co.,  and  Schwarschild  &  Suls- 
berger : 

"  Neutral  or  No.  i.  oleo  oil  is  made  from  the  following: 

Gaul   fat,  ruffle   fat,  gaul  piece   of   gut   end,   briskets 

trimmed  from  the  bed  pickings,  crotch  trimming  from  the 

bed  pickings,  paunch  trimmings,  pluck  trimmings,  reed 

trimmings,  heart  casing  fats. 

No.  3  or  third  grade  oil: 

Head  fat,  fat  trimmed  from  cattle  heads  when  checking, 
plucking  sweet-bread  trimming,  liver  trimmings,  bladder 
trimmings,  fat  from  chilled  beef  tongues  when  they  are 
trimmed,  miscellaneous  fats  from  other  departments  which 
are  kept  clean,  the  first  washings  from  the  oleo  press  cloths 
before  soda  has  been  used,  scrap  vat  skimmings  from  the 
second  grade  oil." 


The  following  formulas  are   for   making   butterine   or 
oleomargarine  of  three  different  grades: 

FORMULA  FOR  AND  COST  OF  HIGH  GRADE 
OLEOMARGARINE. 


Material  and  quantities. 

Cost  per 
pound. 

Total  cost. 

526  Ibs   No    i  oleo  oil 

$0  o87S 

$4^    IO 

476  Ibs   No   i  neutral  oil   .  .  . 

o  08125 

^8    57 

<o  j?als    30  per  cent  cream  .... 

o  42 

•3Q     24. 

300  Ibs   creamery  butter  

o  28 

84  oo 

Labor  and  package  

O   OI 

I  ^    OO 

Salt  and  color        

o  oo 

I    OO 

Total                       

$214  oo 

This  formula  will  yield  1500  pounds  of  butterine.    There- 
fore the  cost  is  $0.1426  per  pound. 


OLEOMARGARINE 


283 


FORMULA  FOR  AND  COST  OF  MEDIUM  GRADE 
OLEOMARGARINE. 


Material  and  quantities. 

Cost  per 
pound. 

Total  cost. 

525  Ibs   No   i  olco  oil                       

$0.0875 

$45  .  93 

475  Ibs   No   i  neutral  lard               

0.08125 

38.60 

40  gals   30  per  cent  cream   

0.42 

40.32 

Labor  and  package                    

O.OI 

12.00 

Salt  and  color                             

o.oo 

I  .00 

Total                                         

$137.80 

This  formula  will  yield  1200  pounds  of  oleomargarine. 
Therefore  the  cost  is  $0.1142  per  pound. 

FORMULA   FOR  AND   COST   OF   LOW  GRADE 
OLEOMARGARINE. 


Material  and  quantities. 

Cost  per 
pound. 

Total  cost. 

350  Ibs   No    2  oleo  oil                   

$0.08 

$28.00 

250  Ibs   cottonseed  oil                    

0.04 

IO.OO 

450  Ibs   neutral  lard                      

0.08125 

36.54 

60  gals.  2\  per  cent  milk  
Labor  and  package  
Salt  and  color      

0.12 

7.20 

I2.OO 
I  .OO 

Total 

$94  74 

This  formula  will  yield  1200  pounds  of  oleomargarine. 
Therefore  the  cost  of  producing  and  packing  for  shipment 
will  be  $0.0789  per  pound. 

From  the  above  it  will  be  seen  that  the  extra  prime, 
yellow  cottonseed  oil,  known  as  butter  oil,  is  not  used  in 
the  best  grades  of  oleomargarine.  This  agrees  with  what 
Mr.  Jelke,  a  manufacturer  of  oleomargarine,  stated  be- 
fore the  agricultural  committee,  that  they  did  not  use 
cottonseed  oil  in  their  best  grades  of  oleomargarine,  as 
it  injured  the  flavor.  Consequently,  he  stated  that  the 


284  DAIRY  TECHNOLOGY 

best   grades   of    oleomargarine    were    white    or    light    in 
color. 

Quantity   of   oleomargarine   produced,1    1888    to    1911 
inclusive : 

v  Pounds  of 

Oleomargarine. 

1899 83,130,474 

1900 107,045,028 

1901 104,943,856 

1902 126,316,427 

1903 73,284,0962 

i9°4 50,199,642 

1905 51,987,336 

1906 554,34,900 

1907 7^366,775 

1908 81,525,600 

1909 92,282,815 

1910 141,862,280 

1911 121,162,795 

Total,  pounds 739,  106,  239 


For  two  years,  from  1902,  the  production  of  oleomar- 
garine decreased.  This,  no  doubt,  is  attributable  to  the 
act  of  May  9,  1902,  which  went  into  effect  July  i  of  that 
year. 

(Annual  Report,  Commissioner  of  Internal  Revenue, 
1911): 

A  great  deal  of  oleo  oil  is  manufactured  in  this  country 
and  exported  to  Europe.  It  is  said  that  in  Holland  there 
are  70  factories  which  get  their  oleo  oil  largely  from  the 
United  States. 

Food  Value.  —  Oleomargarine,  when  made  in  compli- 
ance with  the  laws  of  the  land,  is  a  legally  recognized  prod- 

1  Bureau  of  Statistics,  U.  S.  Dept  of  Agr. 

2  First  year  new  Oleo  Law,  imposing  lo-cent  tax  on  colored  margarine, 
was  in  force. 


OLEOMARGARINE  285 

uct  which  has  its  place  on  the  market.  The  lower  grades 
are  used  in  place  of  cooking  butter  and  the  higher  grades 
(composed  partly  of  butter)  as  a  substitute  for  table  butter. 

There  is  some  difference  of  opinion  among  authorities 
as  to  the  healthfulness  of  oleomargarine  as  compared 
with  butter.  We  quote  two  authorities  as  follows: 

In  record  No.  7  from  United  States  Department  of  Agri- 
culture H.  Lubrig  discusses  the  relative  digestibility  of 
oleomargarine  and  natural  butter.  The  author  reviews 
the  literature  on  the  subject  and  reports  results  of  four 
experiments  on  the  digestibility  of  oleomargarine  and 
butter,  made  with  a  healthy  man  29  years  old  and  weigh- 
ing 175  pounds.  Holstein  butter  and  three  sorts  or  grades 
of  oleomargarine  were  used,  named  according  to  their 
qualities  —  Nos.  i,  2  and  3.  The  tests  were  similar,  the 
fat  in  each  case  forming  part  of  a  mixed  diet  of  meat, 
bread,  vegetables,  etc.  In  the  author's  opinion  the  true 
undigested  fat  was  not  oleomargarine  or  butter  fat,  and 
accordingly  he  believes  it  is  safe  to  conclude  that  butter 
and  oleomargarine  are  completely  digested.  From  a 
physiological  standpoint  the  two  fats  are  thought  to  be 
completely  digestible  and  of  equal  value. 

On  the  other  hand  H.  W.  Wiley,  former  chief  chemist 
of  the  Department  of  Agriculture  at  Washington,  who 
testified  before  the  House  Agricultural  Committee  when 
the  Grout  bill  was  being  considered,  said:  "  This  is  exactly 
what  I  said  in  my  testimony  before  the  senate  committee. 
They  asked  me  if  I  thought  oleomargarine  was  as  digestible 
as  butter.  I  do  not  think  it  is.  I  do  not  think  it  digests 
so  well  as  butter,  because  it  contains  more  of  the  higher 
series  of  fatty  acids,  and  practically  none  of  the  lower 
acids  which  are  more  easily  decomposed  under  the  influence 
of  ferments.  All  digestion  is  fermentation." 


286  DAIRY  TECHNOLOGY 

Oleomargarine  Law.  —  Congress  passed  a  law  which 
became  effective  July  i,  1902.  The  principal  features  of 
this  law  are  as  follows:  Tax  on  colored  oleo  is  increased 
from  2  to  10  cents  per  pound.  Tax  on  uncolored  oleo 
is  reduced  from  2  to  J-  cent  a  pound.  Wholesale  and  re- 
tail dealer's  license  for  the  sale  of  colored  oleo  was  not 
changed,  but  remained  $480.00  and  $48.00  per  year  re- 
spectively. Wholesale  dealer's  license  for  the  sale  of  un- 
colored oleo  was  reduced  from  $480.00  to  $200.00  per 
year.  Retail  dealer's  license  for  the  sale  of  uncolored  oleo 
was  reduced  from  $48.00  to  $6.00  per  year.  A  license 
costing  $480.00  entitled  the  holder  to  wholesell  either 
colored  or  uncolored  or  both;  and  a  license  costing  $48.00 
entitled  the  holder  to  retail  colored,  or  uncolored  or  both. 

Hotels,  restaurants,  boarding-houses,  railroad  contrac- 
tors, and  soldiers'  homes,  schools  and  other  public  institu- 
tions are  prohibited  from  buying  the  uncolored  oleo  and 
coloring  it.  A  family  (not  keeping  boarders)  is  permitted 
to  buy  the  uncolored  article  and  color  it. 

Since  the  passage  of  this  law,  the  manufacturers  have 
learned  to  use  fats  that  will  give  their  product  a  yellow 
color  without  the  addition  of  any  artificial  coloring  matter. 
This  is  done  by  using  fat  from  pasture-fed  animals  and  June 
butter  having  a  natural  high  color. 

However,  many  of  the  States  have  enacted  laws  pro- 
hibiting the  sale  of  yellow  oleomargarine,  regardless  of 
whether  the  color  be  artificial  or  natural.  Another  pro- 
vision adopted  by  several  States  is  that  when  a  substitute 
for  butter  is  used  for  cooking  or  served  as  a  food  in  hotels, 
restaurants,  etc.,  a  placard  shall  be  placed  opposite  each 
table  or  counter,  which  placard  shall  have  the  words 
"  Substitute  for  butter  used  here  "  printed  in  large,  legible 
type. 


OLEOMARGARINE  287 

Detection  of  Oleomargarine.  —  The  spoon  test:  This 
test  is  described  in  the  chapter  on  "  Renovated  Butter." 

Waterhouse  test:  Add  about  5  grams  of  the  sample  to 
be  tested  to  50  cubic  centimeters  of  hot  skim  milk,  cool 
slowly,  and  stir  with  a  small  wooden  stick  while  cooling. 
In  solidifying,  the  fat,  if  oleomargarine,  will  mass  into  a 
lump  or  clot;  but  if  butter,  it  will  not,  but  will  remain 
in  small  particles  distributed  throughout  the  milk. 

Chemical  tests:  In  the  chemical  laboratory  oleomar- 
garine may  be  distinguished  from  butter  by  determining 
the  amount  of  volatile  and  soluble  acids  in  each. 

The  Reichert-Meisel  number  (number  of  cubic  centi- 
meters N/io  alkali  required  to  neutralize  the  volatile 
acids  in  5  grams  of  fat)  is  the  most  reliable  indication  of  the 
kind  of  fat.  The  Reichert-Meisel  number  for  butter  may 
vary  from  25  to  32 ;  for  oleomargarine,  from  .5  to  10,  depend- 
ing upon  the  percentage  of  butter  used  in  the  process  of 
manufacture. 

In  butter  fat  the  soluble  acids  constitute  from  3  to  6  per 
cent  of  the  whole:  in  oleomargarine,  from  .1  to  1.5. 

Butyro-refractometer  reading:  Owing  to  the  difference 
in  the  refractive  indices  of  various  fats  and  oils,  butter 
may  be  distinguished  from  oleomargarine  by  means  of 
the  butyro-refractometer.  This  is  a  very  simple  method, 
requires  but  little  time,  and,  with  few  exceptions,  is  re- 
liable. The  refractometer  reading  of  butter  is  normally 
50  to  54  at  25°  C.  Higher  readings  indicate  the  presence 
of  oleo  oil.  According  to  Wollny,  samples  having  a  reading 
higher  than  54  will,  upon  chemical  analysis,  be  found  to 
be  adulterated.  Pure  oleomargarine  will  show  a  reading 
of  58  to  66. 


INDEX 

A. 

PAGE 

Acidity  of  cream  for  ice-cream 139 

test  for  sanitary  milk :  123 

Adhesiveness  of  milk 2 

Advantages  of  ice-cream  making  in  local  creamery 174 

score-card  inspection  of  farms  and  milk 41 

Aufaits 137 

B. 

Babcock  method  for  testing  ice-cream 188 

Bacteria  in  raw  and  pasteurized  milk 103 

ice-cream 189 

Batch  ice-cream  freezing  machine 167 

Binders  and  fillers  for  ice-cream 146,  186 

Bisque  ice-cream 137 

Bitter  milk 24 

Bottle  pasteurizer 101 

Bottling  milk 104 

Bottles,  washing  of 105 

kinds  of 109 

kinds  of  caps  for no 

Brick  ice-cream 135 

Brine,  system  of  refrigeration 196 

properties  of  calcium  chloride  and  sodium  chloride 197 

Butter  as  a  food 19 

composition  of 20 

from  whey 211 

fuel  value  of  butter  fat 83 

renovated 270 

Buttermilk  as  a  food 17,  234 

artificial 235 

bacillus  bulgaricus  for 236 

composition  of 18,  234 

cream  from 210 

for  cheese 207 

289 


2  QO  INDEX 

PAGE 

Buttermilk  as  a  food,  tablets  and  capsules 233,  237 

use  as  poultry  food 231 

By-products  of  creameries  and  cheeseries 203 


C. 

Calcium  chloride  brine,  properties  of 197 

Can  washer  for  ice-cream  cans 171 

Cans,  ice-cream  packing 171 

Caps  for  milk  bottles no 

Carbohydrates,  fuel  value  of 83 

Carbonated  milk 247 

Casein,  manufacture  of 221 

from  buttermilk 224 

products  from 225 

foodstuffs  from 230 

Certified  milk 50,  55 

amount  produced 56 

commissions  supervising 64 

cost  of  inspecting 63 

definition  of 56 

origin  of 55 

production  of 65 

requirements  of,  in  New  York . .    57 

use  and  advantages  of 64 

Cheddar  cheese,  food  value  of 20 

City  milk  plant 88,  94 

Clarifying  milk 97 

Classification  of  ice-cream 135 

Classification  of  nutrients  in  milk 5 

Colored  milk 24 

Colostrum  milk,  cows' 24 

Composition  of  cows'  milk 3 

kefir 240 

condensed  and  evaporated  milk 261,  262 

kumiss 241 

milk  powder 269 

different  kinds  of  skim  milk 16 

buttermilk 18,  234 

Cheddar  cheese 21 

milk  sugar 216 

colostrum  milk 24 

cottage  cheese 22 


INDEX  291 

PAGE 

Composition  of  human  milk  and  cows'  milk 81 

cream 19 

whey 211 

Condensed  milk 249 

•extent  of  industry 249 

U.  S.  standards  for 250 

processes  and  factors  governing  manufacture  of 253 

composition  of 261,  262 

quality  of  raw  products  for 251 

Cones  for  ice-cream  making 170 

Contests,  milk  and  cream 45 

Continuous  ice-cream  freezing  machine 167 

Cooling  milk  and  cream 141 

Cost  of  pasteurizing  milk , 73 

inspecting  milk 36 

milk,  compared  with  other  foods 10 

Cottage  cheese,  food  value  of 21 

manufacture  of 203 

preparing  milk  for 204 

separating  curd  from  whey 205 

use  of  rennet,  hydrochloric  acid,  and  lactic  acid  in 

making 206 

use  of  buttermilk  for 207 

yield  of 205 

Cows,  number  of  dairy,  in  U.  S 28 

Cream  for  ice-cream 139 

acidity  of '. 140 

fat  contents  of 141 

importance  of  cooling 141 

homogenizing  of 140 

pasteurization  of 140 

Cream,  Moscow  sour 245 

Devonshire  or  clotted 246 

D. 

Devonshire  cream,  preparation  of 246 

Digestibility  of  milk 8,  10 

Diseases  affecting  milk 26 

E. 

Epidemics  spread  by  milk 32 

Equipment  of  village  milk  plant 87 

small  ice-cream  factory 175 


2Q2  INDEX 

F. 

PAGE 

Factories,  ice-cream,  local  creameries 173 

advantages  and  disadvantages  of 1 74 

cost  of  equipping 175 

equipment  of  large  city 176 

Fancy  ice-cream 135 

how  to  make 158 

Fat  content  of  different  parts  of  ice-cream 159 

Fat,  per  cent  in  cream  for  ice-cream 141,  186 

testing  ice-cream  for 188 

Fermented  milk,  kinds,  uses,  and  value  of 232 

Fillers  and  binders  for  ice-cream 146,  186 

Flavor  of  ice-cream,  factors  governing 143 

amount  to  use  for  ice-cream 144 

Food  value,  of  milk,  skim  milk,  buttermilk,  cream,  butter,  cheese,  cot- 
tage-cheese       1,21 

needed  by  people  of  various  ages 17 

requirements  of  infants 82 

Frappes 137 

Freezing  machines 165 

Freezing  point  of  cieam 154 

effect  of  sugar  on 155 

Freezing  ice-cream,  salt  and  ice  to  use  in 150 

speed  of  dasher  a  factor  in 153 

length  of  freezing  period 153 

Fruit  ice-cream 136, 161 


G. 

Gallalith,  manufacture  and  use  of 228 

Gelatin  for  filler  in  ice-cream 148 

Glue-  from  casein 225 


H. 

Hardening  cf  ice-cream 157,  X79 

History  of  ice-cream  manufacture 132 

Homogenized  milk 84 

Homogenization  for  ice-cream 140 

Homogenizing  machine  for  ice-cream 169 

Human  milk  vs.  cows'  milk 81 


INDEX  293 
I. 

PAGE 

Ice  breaker  and  ice  crusher 168 

Ice-cream,  time  of  freezing 153 

freezing  point  of 154 

factors  governing  "swell" 155 

when  to  stop  freezing  and  hardening 157 

how  to  handle  returned  goods '. 157 

fancy,  how  to  make 158 

processes  of  manufacture  in  large  plants 176 

fat  content  of  different  portions 159 

formulas  for  different  kinds 160 

freezing  machines  for 165 

profits  from 175 

machinery  for  making 163 

use  of  homogenizer  for 169 

history  of 132 

freezing  of 150 

classification  of 135,  136 

flavors  and  sugar  to  use 144 

fillers  and  binders 147,  186 

flavor  of,  factors  governing 143 

score  card  for 182 

per  cent  fat,  standard  for 186 

standardization  of  cream  for 180 

testing  for  fat  in 188 

bacteria  in 189 

freezing  by  use  of  brine 196 

Ices,  water  ice,  sherbet,  sorbet,  granites,  punches 136, 143 

Improvement  of  milk  supply 51 

Infant  mortality,  relation  to  milk  supply 30 

relation  to  pasteurized  milk 75 

Infants',  food  requirements  of 82 

Infants'  milk  depots  in  New  York  and  other  cities 52,  53 

formula  for  modifying  milk  at 54 

Inspected  milk 66 

Inspection  of  farms  and  milk  supply 35 

advantages  of 41 

cost  of 36 

of  city  milk  plants 43 

Inspections,  number  made  in  New  York 47 

limitations  of 47 

results  of 42 


2Q4  INDEX     . 

PAGE 

Inspections,  use  of  score  card 37 

Insulation  of  refrigerated  rooms 201 

K. 

Kefir,  preparation  of 238 

composition  of 240 

Kumiss 241 

composition  of 242 

L. 

Lacto,  formula  for 137, 161 

Ladles 270 

Laws  and  ordinances  pertaining  to  pasteurized  milk 78 

governing  manufacture  and  sale  of  oleomargarine 286 

regulating  manufacture  and  sale  of  renovated  butter 274 

Leucocytes  in  milk 125 

M. 

Milk,  definition  of i 

abnormal,  poisonous,  colored,  bitter,  etc 23 

bacteria  in  raw  vs.  pasteurized 76 

modified,  digestibility  of 80 

certified,  production  and  use  of 55 

inspected,  production  and  use  of 67 

chief  nutrients  in 4 

composition  of  cows',  various  breeds 3 

variation  in  composition  of 3 

and  its  products  as  foods ."....  4 

curdling  of 2 

reaction  of 2 

purpose  of i 

properties  of i 

nutritive  ratio  of 5 

palatability  and  digestibility  of 7,  8 

raw  vs.  heated 9 

relative  cost  of 10, 13 

food  value  of  skim •    14 

diseases  of.  affecting  sanitation 25,  32 

per  capita  consumption  in  various  cities 27 

supply  of  New  York  city  for  twenty-five  years 28 

sources  and  conditions  of  city  supply 29 

investigation  of.  in  Illinois 29 

relation  of,  to  infant  mortality 30 


INDEX  295 

PAGE 

Milk,  contamination  of 32 

cost  of  inspecting 36 

inspection  of  city 43 

and  cream  contests 45 

classes  of,  in  New  York 48 

inspected .- 50 

modified 50 

results  of  improving 51 

depots  in  New  York 52 

pasteurized,  advantage  of 67 

home  pasteurized .' 79 

human,  composition  of  colostrum,  normal 81 

manner  of  modifying 83 

homogenized 84 

cooling  and  bottling  in  small  plant 89 

transportation  of,  to  plant 94 

clarifying 97 

bottling  of,  in  city  milk  plant 245 

carbonated 247 

leucocytes  in 125 

condensed 249 

delivering 105 

fermented • 232 

kinds  of  bottles  for • 109 

standardizing,  manner  and  importance 114 

sanitary  examination  of 123 

ropy 245 

sugar,  history  and  manufacture  of 216 

manufacture  of,  in  United  States 217 

by-products  of  manufacture  of 219 

composition  of 216 

powder 264 

advantages,  history  and  development  of 264 

modern  method  of  manufacture 267 

composition  of 269 

uses  of 268 

Mix,  freezing  of  ice-cream 150 

Modified  milk,  use  and  digestibility  of , 80 

Modifying  milk,  manner  of 83 

Moscow  sour  cream,  preparation  of 245 

Mousse 137 

formula  for 161 

Mysost,  manufacture  of 219 


296  INDEX 


N. 

Neapolitan  ice-cream 135 

Neutralizationof  cream 139 

Nutrients  in  milk 5 

in  one  pound  of  various  food  products 12 

cost  of,  in  different  food  products 13 

Nutritive  ratio  of  milk , 6 

Nut  ice-cream 136 


O. 

Oleomargarine,  history,  origin,  and  development  of 277 

manufacture  of 279 

formulas  for 281 

yield  of 283 

amount  sold 284 

food  value  of 284 

U.  S.  laws  pertaining  to  sale  of 286 

detection  and  tests  for 287 

Ordinance  pertaining  to  pasteurization 178 

Overrun  or  swell  of  ice-cream 155 


P. 

Paint  from  casein 226 

Palatability  of  milk 7 

Parfaits 137 

formula  for 161 

Pasteurized  milk 50 

alleged  disadvantages  of 68 

changes  of,  chemical  and  bacteriological 69 

cost  of 73 

advantages  of 75 

relation  to  bacterial  content 75 

increase  of 77 

Pasteurizing  and  cooling  milk  in  city  plant 98 

Pasteurizers,  kind  of 100 

Pasteurizer  for  ice-cream 140 

Pasteurization  of  milk,  supervision  of 77 

laws  and  ordinances  pertaining  to 78 

home 4 79 


INDEX  297 

PAGE 

Philadelphia  ice-cream 135 

Plain  ice-cream 136 

Poisonous  milk 23 

Powder  milk 264 

whey 269 

Properties  of  milk i 

Proteids,  fuel  value  of 83 


R. 

Raw  vs.  heated  milk 9 

Reaction  of  milk 2 

Reduction-fermentation  test 126 

Refrigeration,  mechanical 193 

principles  of 194 

size  of  compressor  and  strength  of  brine 197 

operation  of  plant 198 

Renovated  butter 270 

origin  and  extent  of 271 

processes  of  manufacture 272 

U.  S.  laws  regulating  sale  of 274 

test  for 276 

Ropy  milk 24,  245 


S. 

Sanitary  pipes  and  fittings 171 

Score  card  for  farm  and  milk  inspection 37 

advantages  and  results  of  using 42 

for  market  milk 45 

for  ice-cream 182 

Sediment  test  for  milk 124 

Sherbet,  formula  for 162 

Skim  milk,  value  of  different  kinds 14 

composition  of 14 

Sodium  chloride  brine,  properties  of 197 

Souffles 137 

Speed  of  ice-cream  dasher 153 

Specific  gravity  of  milk "2 

heat  of  milk 3 

Standardized  milk  and  cream 114,  119,  180 

formulas  for  standardizing 113,  180 

Swell  of  ice-cream,  factors  governing 155 


298  INDEX 

T. 

PAGE 

Tests  for  sanitary  milk 123 

reduction  fermentation 126 

acidity 123 

sediment 1 24 

Toxins  in  milk 72 

Tragacanth,  gelatin,  and  Indian  gum  for  ice-cream  fillers 148 

Tuberculosis,  relation  of,  to  milk  supply 33 

V. 

Vanilla  ice-cream,  formula  for 160 

Variation  in  composition  of  cows'  milk 3 

Viscogen  for  cream • 128 

Viscosity  of  milk 2 

cream,  preparing  viscogen 127 

W. 

Whey,  composition  of 211 

Whey  butter 211 

methods  of  manufacture 211 

profits  from 215 

markets  for . 214 

powder 269 

Whitewash  paint  from  milk 226 

Y. 

Yoghurt 244 


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